Everyone is going to have different experiences with all products. But I busted tons of 2010 Knockout and 2012 Knockout. I never got a single card numbered to 8 or less in any of those boxes. Could be bad luck, I dunno.
But I did buy three boxes of Bloodlines when it came out. Got a GSP/Matt Serra dual auto, Jon Jones auto, Rick Franklin Plate Auto, and a Nick Diaz Ruby Auto /8. Just my opinion but I was getting at least one card numbered to 8 or less in each box of Bloodlines. Add to that you can get Ronda Rousey and Nick Diaz LIVE autos and I think I would go with Bloodlines over Knockout. Either that or wait a while and break 2013 Knockout when that comes out.