×2 on Skyjacker. It's a good solid kit. Both Rough Country and BDS are known to do damage to the front Dana35 axle housings with their cheap plate-style extension bracket.
Shocks however are going to be what influences the ride the most (more than brand of lift). I've found the best ride quality nearly always comes with nitrogen gas-charged monotube shocks. Skyjacker offers this style shock as their M95 line. Though I've not had personal experience with them, I would expect them to give a smoother, yet more firm & controlled ride than any of their other options (as well as those offered by most other suspension lift brands too).
The other option (if you are able to order the kit w/o shocks), would be to go with a different (better) brand shock altogether such as Bilstein 5100 or 5125.
Something to note with the Skyjacker kits if you have a V6 Supercab Ranger (you didn't specify), these kits have been known to come up a little short on lift height due to the softer springs and the weight of the bigger cab & engine. Many people choose to go up to the next size lift (6") for this reason which generally provides about 4.5" lift on these trucks (the brackets are exactly the same on both 4" and 6" lifts, only the springs are different). This should avoid having to put leveling spacers under your front spring seats should the lift height not come up to expectation.