Peters Gallery is very helpful. In regards to his gallery and what you are looking for my take is this:
18-70mm pictures do not have quite as crisp, clean and and as professional look to them as the 12-24mm pics do. Most pros would call it the bouquet I think. The edge to edge clarity and smoothness. I like the 12-24mm better.
The 10.5 is very different but I think is a slight step up in overall quality on the 12-24. Owining one and only shooting about 70 pics U.W so far I can attest it is great in low light situations giving good depth if field even at 2.8. It also focuses at inches from my dome. You really have to get close with this lens but it is really nice and a performs great at over and under shots.
U seem to have a lot of gear and I assume experience, maybe sell off some older stuff and get both the 12-24 and 10.5 but I would lean toward the 10.5 if I were you. I will also point out the 17-55dx, as another choice, the finest zoom lens I have used on land. Will be testing it U.W. soon.