[url="http://www.insanelymac.com/forum/topic/279450-why-insanelymac-does-not-support-tonymacx86/"]#####[/url] used? upload in mediafire...
recomend card for buy now...
Which bootloader you use is fairly irrelevant as you are not going to use any form of graphics enabler. So unless you are using a sandy bridge processor then I would go for Chameleon RC5 and remember to not use the GraphicsEnabler option.
All of those 6870's look like reference cards, I have the 1st one on your list I believe the Sapphire however I flashed it to a slightly overclocked XFX bios but in short any of those 3 cards should work just fine so just buy the cheapest one!