If you are planning on replacing the gas block, get the Adam's arms kit. It's the most popular meaning you'll have no problem finding a matching handguard. It's also easy to clean, plus the skis and bolt spring on the carrier pretty much eliminate carrier tilt. No signs of it on my rifles. Also, they have a great meloniting process on all of their parts, makes for easier cleaning and maintenance.
If you are cheap, get the kit from CDNN, it's an adams arms kit minus the bolt carrier. You'll get carrier tilt and you'll have to occasionally tighten the gas key screws. But it's cheap as hell, like $170. You can try it out, then buy the adams arms carrier later.
If you want a drop in kit, get the Osprey system, you don't have to remove the gas block and it's pretty easy to install. Non-existent handguard selection though.