My pops has them on a Sahara Edition Jeep. I've driven the vehicle with the Monroe's and haven't had any complaints about them. I guess they do the job. The jeep has a naturally rough ride so if the shocks weren't that good then it would be a whole lot worse, I guess. I probably wouldn't put them on my SS but again just my opinion. Hope others will chime in. For the jeep they are good/average.
Are you talking about Monroe's Severe Service Shocks? The forum does not have much experience (bad or good) with either these, or NAPA's Gas Magnum Shocks. They cost about the same as the KYBs.
Many experiences and reports of the KYBs suggest that they give up, or worse, after about a year or so. If you get a lifetime warranty, and it includes labor - or you do them yourself - it's your call.
So far, I don't know of anyone who has replaced their Bilsteins because they needed to be replaced; rather, they tried adjustable shocks. Bilsteins aren't cheap, but their reputed longevity makes them cost effective.