As others have said it's a very subjective thing but....
When faced with a simialr choice a couple of years back I went for the Leica Duovids 8+12x42s - they are cracking bins, fantasticly bright and sharp at both mags. The only downside would be the weight of them (not that it bothers me - although they're heavy they are v. well balanced), so if that's an issue I'd recommend 8x42 Ultravids.
Optically all the top brands are excellent, so try them all, it may well be the feel in the hand that decides you.
When faced with a simialr choice a couple of years back I went for the Leica Duovids 8+12x42s - they are cracking bins, fantasticly bright and sharp at both mags. The only downside would be the weight of them (not that it bothers me - although they're heavy they are v. well balanced), so if that's an issue I'd recommend 8x42 Ultravids.
Optically all the top brands are excellent, so try them all, it may well be the feel in the hand that decides you.