Having had a number of BOTH Bs and pre-Bs, I'd say it's really a matter of personal choice. I've paid as much as $600 for a NIB pre-B, and as little as $375 for a very nice pre-B. And, I've paid varying amounts for pre-B 85s (and the 85 Combat and the equivalent, before it was called that.)
Right now, I have an 85 Combat (no firing pin block), a semi-custom 75B SA, a highly customized AT-84s (a clone), and a Sphinx. All are the same basic design. The Sphinx and the custom AT are the best of the bunch, but I paid more for them.
Personally, I'd rather find a used B, and have a good gunsmith work the trigger.
The B won't look as good as the pre-B -- the newer design trigger guard looks funky -- but there are a few parts that are increasingly hard to get on some of the older pre-Bs (having to do with the safety lever on some models.)