Both began as plot devices for crossovers.Question is,has either one gained any depth since then?

Oddly enough, I've never read a comic where either one of them was the main villain.

Bane has been given a lot of depth and become a really good villain, far better than in the old Knightfall days, at least to my mind. Some writers handle him better than others, of course.

Doomsday....there was an effort by Supey writers in the early 2000s to give him some intelligence, but for the most part he has only ever been a mindless brute.

Bane, an evil Doc Savage, is a cool villain. Doomsday is a poor man’s Hulk, though he does look cool.

Before Knightfall there was an entire extra-length special comic setting up Bane's history and what led him to seek out Batman in the first place. It was pretty good. So easily Bane, since he was actually developed (and has continued to be over the years).

Doomsday was introduced by punching out of a hole in the ground. The creators themselves said they didn't know what he would look like without his coverings, where he came from, or anything at all. He was only a battering ram. Later attempts to explain him were ham-handed and dumb, IMO. He just wasn't that good.

Yeah, the origin for Doomsday sucks ass.

Has to be Bane, for all the reasons already stated. I enjoyed that whole Knightfall thing at the time.

Yeah, it's Bane. Doomsday was a walking plot device. Even before the Nolan movies, Bane had more going on upstairs than a lot of people gave him credit for.

Bane. Character was fleshed out prior to Knightfall, and developed as a character since.

Doomsday should have been a one-shot plot device. He killed Superman. Any appearance after that where you know Superman is going to beat him just doesn't work. Has a terrible origin as well.