1. Zach Galifinakis
He doesn't really tell jokes, he is more of a guy who acts funny. His mannerisms and delivery are what sets him above the rest. I love how he can be a dick to people and make it pure gold. For an example of this see his web show thingy Between Two Ferns on Funny Or Die. The last one he did with Ben Stiller was great. To see him act weird watch The Hangover or him on Tim & Eric. Actually here are some links.
http://www.adultswim.com/a
http://www.funnyordie.com/

2. Demetri Martin.....Ladies
He has some similarities in the ways I find Zach funny. Not that he is the same, just my sense of humor lends me towards his stuff. Like it's a lot of the way he acts when he tells his jokes. Also I guess he is a prop comic when I think about it, but way better than Carrot Top. I guess I like my comedians like i like my music, "Alternative".

3. Patton Oswalt
His stories he tells in his stuff are great. Do you know why he quit LSD? So the 1st memory his daughter has of him won't be him high telling her the truth behind Lucky Charms. He is also a geek and likes the same junk I do. He was pretty good in Ratatouille too. You know what, I REALLY wish The Comedians of Comedy was still on CC, that show was really good and had both him and Zach G on it.

4.Mitch Hedberg
Again with his delivery. While he doesn't have too much stuff because he is well dead, it was still good. Actually this got me thinking about people who do have lots of stuff and that in their day Steve Martin and Eddy Murphy had some really great stand up acts (which you should watch), but they are both way past that time now.

5. Dane Cook
I KNOW, I know... He is kinda a sell out now and he hasn't had any real good material in a while and he sucks now along with his movies (except Waiting, but he's not good in it Ryan Reynolds is). BUT his old stuff was great, and I still quote him occasionally. Like calling Burger king the BK Lounge.
 
Edit: I forgot, somehow, about Lewis Black. He is the real number 5.
  The guy is pure genius. I love his yelling and his jokes are great. Does anyone have minutes of pure gold on nothing but candy corn? I think not. He has also seen the end of the world and can tell you where it is.