Top 5 Roles?

Spot on

The Master
Two Lovers
Inherent Vice
Her
Joker

That's damn tough, Phoenix is one of those actors that's great in almost anything he's in.

I do a top 5 of his truly get roles and some Underrated ones

Top 5

Arthur Fleck- Joker
Freddie Quell- The Master
Johnny Cash- Walk The Line
Joe- You Were Never Really There
"Joaquin Phoenix"- I'm Still Here

Underrated

Leonard- Two Lovers (one of his best films, doesn't get the love it deserves)
Theodore- Her (many will find it weird I have it on the underrated side, I don't think cause it isn't as intense as his other roles, it gets the love it deserves)
Bruno Weiss- The Immigrant

I've only seen one, and that was Walk the Line where he played Johnny Cash. Brilliant!

Joaquin Phoenix won the Oscar for his role in the Joker!!!

Not mentioned here yet, but a great job by Joaquin and a VERY underrated film, “Return To Paradise.”

https://www.imdb.com/title/tt0124595/