2 gtx 295s, no doubt, the gtx 285 core would have to be more than 30% faster than the cores in the GTX 295, also the two GTX 295s would equal a greater total frame buffer amount. the gtx 285s would run out of frame buffer first if the resolution and AA was pushed too hard.
btw, the link you posted is with 3 GTX 280, not 285
the top scores for 3dmark vantage is held by a quad-sli setup:
http://service.futuremark.com/resultComparison.action?compareResultId=692064&compareResultType=19
keep in mind though that 3dmark is optimized to use every bit of system power, unlike a lot of games, it sees significant improvement with each additional GPU, almost all games are unable to make full use of 4 GPUs, so the subject is debateable as to which is better, as far as which one has more power though, it would definately be the GTX 295s in quad-sli.