Personally, I like the look of the Dev Alpha B better, although the L is clearly more polished/refined hardware-wise.
I think BB10 will do extremely well and compete not only with WP8, but also the aging iOS platform.
BTW, they are releasing a keyboard version which is the N-Series. they are going to handle the Alpha Dev. C which has a physical keyboard… and as a rumor they have come out leaks of documents mentioning an R-series ….