I think the classified is the best followed by the lightning. The HOF benchmarks very well but a lot of folks at HardOCP have had significant issues with the card - check the thread over at HardOCP before buying. It could very well but a PEBKAC issue, but i'd read through that. However, the benchmarks on the HOF are pretty darn amazing. Hard to ignore the performance and out of box boosts it apparently produces.
Anyway, IMO, the lightning and classified are the best because they both allow over-volting while the HOF does not. Also, the Zotac AMP! 780 is out of consideration because it definitely not have OV capability. Keep in mind, getting the special edition of afterburner for OV'ing the lightning isn't as straightforward. You'll have to email MSI and ask them for it, apparently, although I haven't heard of anyone being turned down.
Also, is it just me do both the HOF and lightning both look pretty cheesy? I loved the aesthetics of the 680 lightning but the 780 lightning....I DUNNO. Don't like that weird looking middle fan.