I've used sumo's, timbrens, timber groves, and airlift 1000's.
The sumo's & timbrens are great with a trailer attached, but really ruin the ride of the truck. They do keep you more level, but thats about it.
The timber grove are a little better because you can lower the air with no trailer, however, even with minimal air, they still have the rear end "kicky" when unloaded..I guess if you don't drive like a moron over speed bumps and train tracks, its ok, but for me, I thought they were too bouncy when unloaded. I will say they are super heavy duty and a great kit for a trailer. Probably the best.
The airlift 1000's, in my opinion give the best ride when unloaded. They aren't as heavy duty as the timber grove, but when you deflate them, you can't really tell they are there. Yes there may be maintenance, but airlift lifetime warranty's them and will send you free replacement bags if they break. I've had to change mine before, one blew out. I might have over inflated it, not sure.
So, sumo & timbren are the easy way, but the worst ride quality all the time.
Timber grove are super heavy duty, ride is ok, but can be bouncy at times loaded or unloaded.
Airlift 1000s not as heavy duty, but best ride.