Here is my .02 cents, I was in the same situation as yourself for months and just recently pulled the trigger.
I was originally leaning towards the RCX 5" or the Skyjacker 4" but in the end I couldn't bring myself to cut the frame on my brand new truck. When I looked into the Zone lifts I found that they require you to cut a lot more than just the crossmember ears on the frame. I figured that if I don't like what I went with I can always upgrade down the road when most of my warranty is gone.
BDS looks like a great lift, personally I just didn't want to spend that kind of money and as Payton34 mentioned it will widen your track width. Again, it's only personal preference but I didn't like the idea of my front tires sticking out a little wider than my rear (and no, I'm not a fan of spacers, even in the rear).
So with this being said I started looking at combo lifts. I narrowed it down to either the RCX 3.5" suspension with 1.25" body lift or a 2.5" leveling kit with 1.5" zone body lift. Both allow you to run your factory 20's and both will accommodate a 33x12.50 tire. The RCX 3.5" does require you to notch the front crossmember, but after a little research I found that a new crossmember is only $85. Call me paranoid or foolish, but I just like the idea that I can revert the truck back to a completely stock setup if I choose. I found no negative points to going with the 2.5 leveling kit and 1.5 body lift. But in the end I chose to go the RCX route, mainly because it does provide differential drops, the lift is almost an inch bigger and because the gaps with the body lift will be just that much smaller.
Hope this helps a little as I can relate far too well with not knowing which direction to go.