If you watch the video(don't worry guys, I have the link) with Doug and Ethan, Ethan says "the first thing you do when you get it is remove the weights then you have a perfect knife" then laughs although I suspect he meant it. Go to 8:50 to hear that quote:
https://youtu.be/tVsRcOb8oG8
I don't own a 10 but I love my 12 and I agree with Dex about preferring it over all others but I'll add for all around average use. I love the 9 and 4 for work but I'm going to just grab a knife to carry just to have it in case of whatever, I pick the 12. I know none of that helps for the OP question but that just my 2 cents on the 12.
I'll add that from a collectors POV, I collect them and use them, the 12 is harder to obtain and is currently available while the 10 is easily obtainable.
So,10vs12, I say 12 because I like the shape and size, I prefer the drop point to the clip point, the 12 is currently available, you get a chance to be experience a Becker that's not a KABAR, if you choose not to keep it you'll have no trouble recouping most if not all of your money depending on your timing.
I have handled the 10 and have nothing negative to say about it, I will admit that I'm fully biased as a 12 owner.