I'd personally go with the skyjacker economy lift out of those two...
I dont have personal experience with the other kit you're talking about but i've ridden in a few with different skyjacker setups and the rides have been nice for a lifted vehicle. Also seems to be a popular choice among different threads i've read
Most popular i've seen are the Rough Country lifts (as above) or Rubicon Express lifts.
here is a link with two reviews of the 4" economy lift (post number 31 and 34)