Any comic fans want to recommend me good comics to start reading. I mainly interested in Marvel stuff but DC and others are good suggestions too. Is there a site or other resource you use to read comics online ??
I guess I *might* have a few opinions on the matter, let's see...
So other folks have pointed out a bunch of a ways to read things online, and really if you just google "read *insert comic*" you'll find what you're looking for. (It might run terrible on mobile, though). Linking directly to piracy sites is against one of RGT's rules, but it's pretty easy to find on r/piracy and whatnot.
There's also the legal option, Marvel Unlimited; it's a yearly sub, the comic reader on the app works well, and the selection is genuinely *massive*. They haven't put everything on there yet, but you'd never run out of options. I've cut a lot of things out of my budget, but Unlimited is some pretty great value. (They also curate stuff to try out occasionally, and put in enough effort with tagging the available books that the search function works pretty well). The latest books go on there three months after release, so sometimes I would read something I loved on Unlimited and then dash off to the local comic shop to buy the latest stuff just to keep the story going.
Now, for the eternal question of *what* to read? The "anyone reading comics?" thread has a lot of suggestions in it already (and it might simply be an outlet for me to talk about the new comics I read each week, natch), but the answer for me growing up was "whatever looked interesting". You'll never really be totally up to date on the continuity, clocking every side character and their current status in the world. Thing is, if the writer is up to snuff? None of that matters, they'll make a fun story regardless. Pick a character you like and want to read about, or just grab a cover that looks cool!
....
..
.
Yeah, I can recommend some specific comics though, I'm not gonna be totally boring!

For Spider-Man, it's hard to go wrong with the writer Dan Slott. I believe he's written more issues than anyone else living, and a lot of it's pretty great. Specifically, we're looking at runs (collected as trade paperbacks or TPB's, which you can purchase or "find" if you want one big book instead of single issues) like, in order,
Big Time,
Spider-Island,
Ends of the Earth, and
Dying Wish. After that, for *reasons*, the book becomes
Superior Spider-Man for a couple years. It's a really wild story, any of which is fun. Past that, there's
Spider-Verse, though as a warning that story doesn't resemble the movies they helped inspire.
Here's a more comprehensive list for Spidey, if you want some specific stories to search for by name or if you'd like to follow the order they were released in.
The Spider-Man comic books definitive issue-by-issue collecting guide and trade reading order for omnibus, hardcover, and trade paperback collections. Find every issue and appearance!
www.crushingkrisis.com
Don't get too hung up on being thorough or following a list though, that's just useful for reference.

When it comes to the Fantastic Four, it's hard to start anywhere but with Stan Lee and Jack Kirby. Specifically,
The Coming of Galactus. Space God is coming to dine out on Earth, and it's up to four clowns in spandex to ruin his meal. They've tried to adapt this twice already, and the upcoming MCU film looks to be dipping into the same well. It's like the Dark Phoenix Saga in that sense, the one story that everyone who likes these characters brings up without fail. It *is* a good story though, so long as you vibe with Stan Lee's pseudo-Shakespearean dialogue.
More recently, Jonathan Hickman is maybe my favorite modern FF writer, and his run on the main book tied into his later Avengers/New Avengers series, which are the basis for
Infinity War if you enjoyed that movie. Eventually all of his story threads paid off in the event
Secret Wars, which has a big climactic standoff between Reed Richards and his rival, Dr. Doom.

These collected editions are just called
Fantastic Four by Johnathan Hickman and then a volume number, for the most part. Also, the first two volumes primarily feature the art of Dave Eaglesham, who has a very "classic" comic style, he's a bit like Capeshit Norman Rockwell. His stuff is great here! The only thing to keep in mind is that this run comes at the tail end of Marvel's
Civil War event. It was a little bit like the movie, in that all the heroes took sides against each other; in the aftermath, Reed Richards becomes obsessed with figuring out how disasters like that can be avoided; Hickman's Reed spends a lot of time grappling with how best to serve the world, while still being present with his family.
Here's another resource for searching for stories and the like!
Following "Secret Invasion," the 2008 crossover storyline, came the "Dark Reign" era which leads to a shift of power in the Marvel Universe toward
www.comicbooktreasury.com

Finally, the X-Men! They're a bit weird, the original stuff is actually pretty miserable. No one cared that much until they get the sexy revamp by Chris Claremont, who was pretty the Lord High Author of good X-Men stories for years.
Dark Phoenix,
Inferno,
Days of Future Past,
The New Mutants, Rogue, Psylocke, Gambit, Kitty Pride, Mystique, Emma Frost, Jubilee, Sabretooth, most of the interesting shit about Wolverine? Several people contributed to the X-books, but Claremont was the lead writer and generally regarded as the creator of allllll of this shit. He brought soap opera-drama to Xavier's School for Gifted Youngsters, and we're all the richer for it. Literally, in the case of movie and tv studios that adapted his work wholesale.
All that said, maybe dip a toe in? He's very wordy, very dialogue-heavy. Claremont's X-Men were talkers, and after years on the same books he could get pretty heavy on his own continuity. He occasionally dips back into comics just to resume the stories he left back in the 90's, like none of the intervening decades ever happend. (I think that's part of what inspired
X-Men '97). Basically, try it from the early stuff, and then keep going if it's working for you.

After Claremont, the next big thing in X-Men was Grant Morrison's
New X-Men, with artist Frank Quitely. Mutants became a genuine subculture, and the stories were wild with imagination. Emma Frost became a genuinely interesting character, Cyclops and Phoenix's marriage got
complicated to say the least, and future writers got inspired for decades to come. Morrison had revamped the Justice League for DC just a few years prior, and he gave the same life-giving aid to the X-Men here. It's often too weird to describe, just try it out!
Two more quick rec's for Marvel's Mutants:
Astonishing X-Men by Joss Whedon, and The Krakoan Age, starting with
House of X. Astonishing is just a great adventure that's nostalgic for Claremonts work, but adapted for a modern audience. (The art by John Cassaday is incredible, too). It's probably the last story to do anything interesting with Colossus too, if that's a character you enjoy. Krakoa, on the other hand, was a huge step in a new direction for the X-lineup in general. Basically all the mutants start a country, and start taking major geopolitical steps to undo their persecution in the world. It's such a big idea, that despite years of different books and writers it still feels like they didn't really tap it's potential.

Like before, here's some references for specific titles of books and reading orders if you want to keep with a story!
The Dark Phoenix Saga, Days of Future Past; It all starts here with Chris Claremont's 16 year run as writer on X-Men! Here's the order for best reading!
www.comicbookherald.com
From Grant Morrison's New X-Men through Joss Whedon's Astonishing X-Men, it's been a good last 15 years to be an X-Men fan. Catching up? Here's the guide:
www.comicbookherald.com
The definitive guide on how to read and collect every series in Jonathan Hickman's era of X-Men. Plus: 20 must-read stories to prepare for Hickman X-Men.
www.crushingkrisis.com
That's a few things to go on, and no doubt myself and others will be happy to ramble on if you have any questions or just like a particular book and want to talk about it! There's a lot of great DC comics as well, and loads of things from other publishers of course.
(I'm reading a book right now called
Kill Train, where a mother on the verge of a mental break finds out that her subway train has been randomly selected for murder, as part of some dystopian population control measure. The government releases loads of homicidal maniacs to slaughter the passengers, and just hoses it down at the end of the line. After a pep talk from a college friend unfortunate enough to be on the same train, our protagonist rallies some would-be victims and weaponizes her fragile mental state to kill the bastards first. Surprisingly more funny and crowd-pleasing than it sounds!)
Locate a run of the Groo the Wanderer that Marvel/Epic put out in the 80s, and enjoy
Okay ignore everything else and do this. My cousins gave me Groo comics to read growing up, and now I'm an adult who still reads this shit. Clearly, it works.