In points-based leagues, you can easily compromise to include both elements. I like IP getting in on the action for points based leagues as well. With W, IP, QS all having value you have a fairer, all-around, representation of points given actual performance.
In Roto I'd say you are better off stick with Wins. If you want to tinker with it just use net wins. This stat allows great season long strategy, giving middle releivers a place in fantasy as well. Going to QS in Roto would require adding holds to keep middle releivers relevant. Since they are relevant in the actual game, I feel they should have a place in fantasy as well.
In H2H leagues QS gain more momentum imo because it is weekly. I'd still stick with Wins, but the fact you can have a dominating pitching week but end up with no Wins to show for it and lose that cat for the week is frustrating at times. I'd want to see holds added if you went to QS.
I like the creation of a single relief cat that combines Saves + Holds + relief Wins - relief Losses - BS. not sure what you'd call it, maybe something like relief pitching efficeincy or effective relief pitching. This would reduce the value of closers in general and make the relief pitchers who are the best at getting batters out the most valuable regardless of what role or inning they pitch. We don't create a stat for hitters' AVG w/RISP after the 7th inning. Yet that is similar to a save opp or hold for a hitter.