For example in Generations Shatner is pretty much in the background, he's overwhelmed by the others because they're much better actors. Or is that just because Shatner's terrible?
The only Next Gen actor Shatner shared the screen with was Stewart and he more than held his own and he would've thumped Frakes, Sirtis, Burton, Dorn and McFadden if he'd been on screen with them.
He also shared the screen with Malcolm McDowell. Had the scenes on the Enterprise-D been going on at the same time, they would've held my attention a lot more.
I disagree though, I mean Frakes isn't brilliant and McFadden was pretty underused but they're still better than Shatner imo. His performances never seem natural to me, it seems like he's just trying to get attention and it falls flat on its arse with me.