It's very difficult for me to say which anime is my favourite, but if I had to make a list, it would be this:
1. Cowboy Bebop (just an absolute masterpiece in every sense of the word, from the soundtrack, to the story, to the characters, to the environment, to just about everything in the anime is just so exceptionally well made).
2. Samurai Champloo (I think this is the most unique anime I have ever seen, because it just mixes topics so out of touch with each other that you would think they wouldn't mix but yet they do so well, absolute masterpiece).
3. Trigun (just an amazing experience through and through, from watching the characters grow to the final ep that ties everything so incredibly neatly, amazing, amazing anime that I really should start re-watching).
4. Pluto (Now Pluto is an anime that many didn't really like as much as I did, but idk, I just think it does the detective—mystery genre so incredibly well and just is a breath of fresh air from the slop we see nowadays).
5. Beck: Mongolian Chop Squad (Now this I have to say is the most underrated anime I have ever seen that seemingly nobody talks about, it's such a good music anime and just the journey of the main character coming from not knowing what to do in life and finding music out of nowhere and through sheer want and need and hardwork becoming someone who ends up becoming someone special is just something I relate to on so many levels. Absolute masterpiece to watch).
Honourable mention:
Daily lives of high school boys (now this anime I have rated a 9/10 mainly because it's just a comedy anime that, at the end of the day, doesn't really produce much deep thought. However, this is not to say that it's a bad anime; rather, I would go as far as to say it is the best comedy anime that currently exists, full stop. It's just an absolutely amazing anime that makes you laugh non-stop from the start of the anime to the finish. I would honestly go as far as to say this is a must-watch for anyone who is going through high school or is about to graduate, because of just how good it reflects the childhood carefreeness that high school offers. This, coupled with the fact that high school is the last checkpoint in life where one can be carefree and have this childhood freedom, is the reason why I recommend watching it during or as you are graduating from high school. Amazing, amazing anime.