Like everyone else is saying, it depends on the application. If you don't have some decent mics yet, then most likely you'd be more pleased with a 57 and a B1 combo.
I was trying to stereo mic a guitar amp recently on a demo I'm working on using a 57 clone and a nameless 58-type mic and it really turned out to be more trouble than it's worth if that's what you're trying to do. I found it's much better to do a mono track with the 57 and then stereo-ize it with some ultra-short, but wide, stereo delay. Or better yet, record a second guitar track ala the good old days and put them opposite one another in the mix. You could clone the mono track and off-set it ever-so-slightly and alter the EQ as well.
If you're doing acoustic, then a 57 and B1 could produce some interesting results, albeit a compromise in favor of having the two different types of mics for other purposes. Ideally, for acoustic, you'd probably want two condensers unless you're like me and rarely pay attention to conventions where they make life too difficult (as in: I need two good mics for a variety of applications, therefore instead of limiting myself with two condensers, I'll make do with a dynamic and a condenser).
If having a good dynamic lying around isn't all that important, then I'd go with the B1 and v67 because you could certainly use the B1 on an amp and both for stereo acoustics. The v67 would be helpful when you have a vocalist with a flat voice like me, at least from what I have gathered as I don't own one personally, but have heard them and read the comments on them. Or, if you think you'll need a stereo pair, I'd recommend two B1s over the v67s.
Take all of this for what it's worth. I've been labeled a Hyatt lacky by these people.
