Well, since I want my cell phone to be a PHONE, and not a computer, camera, pda, etc.......
My vote goes to my trusty 5165. Best reception, best keypad layout, and able to take multiple drops to concrete from as high as 15 feet without damage.
AT&T recently gave me a 2260 to replace it and I used it for a couple of months but there is no comparison. Terrible reception, and many people say I sound like I'm in a tin can. I bought a new keypad for the 5165, and switched back.
I did recently buy a 6200 for my overseas travel, but haven't tried it out yet. I do think the FM radio will be cool if I can somehow use real headphones with it.