I like a lot of the old HK stuff from the 70s and particularly 80s but at heart I'm a complete Bruce Lee fan. Even though he only made a handful of films he remains the most charismatic, magnetic martial arts star we've ever seen. Only Bruce Lee is compelling enough as an onscreen presence to hold the screen in all the non-action scenes. Lots of others have come and gone, and many have had incredible skills but none have had that special presence that makes Lee a genuine legend.
Other than that I'll take pretty much anything from Jackie Chan's heyday. Pure entertainment, though the comedy interludes are usually cringeworthy. Tony Jaa's stuff is pretty amazing, and Ong-Bak is a great, entertaining film with awesome action scenes. Warrior King is complete nonsense and suffers a bit from that.
I must admit I'm quite in the dark when it comes to Jet Li - I just never got round to watching much of his stuff.
Came across a bit evangelistic there... I mean, I love the films and the films only - I'm not the sort to have a pair of nunchuks hanging over my bed or anything