Hmmmm... I like so many breeds but my top three would be:
1. Arabs - I have owned a few and loved them all
2. Friesians - never owned or worked with one, but they are beautiful
3. Welsh - I have a Welsh cross and she is tons of fun
It is hard to choose specific breeds because there are some really good and some really bad specimens in all breeds. I prefer those horses that are truer to their breed characteristics and show the charisma and conformation of their breed. I also like some crosses, but again, mostly those where the best of the blended breeds appear (i.e. A Friesian cross that is actually built like a Friesian).