Based on my limited experience, 10" cones don't focus the low frequencies very well. I'm a fan of 12" cones but you gotta match your set up to the character of your bass. I think 10" cones might sound better with a bright sounding bass like a Spector or Pedulla. 12" cones would sound better with a lower mid prominent bass like a Stingray or Warwick, 15" cones are good with p-bass and the thuddier kinds of vintage designs.
I love my EBS neo212, it seems to be all things to all my basses. For a bass that is midscooped like a jazz, a 2x10" and 1x15" offers a nice combination too.