Blackfire has a nice, oily shine, but lasts only about a week or so. It's a good idea for garage queens that have a really thick clearcoat and need SMR-grade abrasives. Oh, and if you apply BF like a wax (no breaking down the abrasives to remove swirls), its really easy to work with.
Klasse lasts forever, has a great shine, excellent depth, good clarity, and isn't overpriced. There are rumors and uncertainties about it's beading, slickness, hazing, and ease-of-removal. Stick with CMA or jimwh's Klasse application tips and you should do okay. I'd have Klasse over BF any day.
Good luck, and don't forget the Zaino system. It is expensive at first; a PITA to learn how to apply thinly, properly mix, and read through the few pages of instructions, but the work is well worth a wonderful shine in the future. The beading, shine, slickness, and car-wash-in-the-rain-effect will last longer than Klasse too.
http://www.yosteve.com for Klasse sample kits and MFs
http://www.properautocare.com for everything but Zaino
http://www.premiumautocare.com for Klasse, Platinum, P21S...
http://www.zainobros.com for Zaino
http://www.zainobros.com minus ZFX, plus Corvette parts
wet@zainobros.com for your nearby distributor