I would think it's Gasquet. I've never seen him really crush the ball off either side, forehand or backhand. Not only that, but Richie's just not a physical player. He doesn't grind any of his opponents down. Hell, he doesn't even have much of physical build to hit the ball really hard or grind down his opponents. Even Almagro is stronger than Gasquet, and that says a lot.
He did have a really good win against Roddick in the Wimbledon 2007 Quarters coming back from 2-0 sets down If I remember right.
Gasquet does have a very potent overhead smash, though whether you need much strength for that I dont know.