I prefer Schallers to Dunlops just because Im a Schaller kind of guy
But seriously, if you get the Dunlops, get the dual design ones because you can use them as straploks or just regular strap buttons. They have the wide flange thing that a regular strap button has so you can just stick on a strap without a lock. The only problem is they look ugly
I have owned the Original Design Dunlops, Dual Design Dunlops, and now I am using some black Schallers. I think Schallers are the best looking and most reliable ones because they way they hold the strap on. Even if the mechanism fails, you still have the little U clip holding the bass up. And as long as you have the nut screwed down nice and tight, that U clip won't move at all. Dunlops don't have these U clips, but they have this mushroom-shaped male part that goes into the little recepticle part on the bass and locks with 4 ball bearings. If these get stuck open, your bass WILL fall down.
If you think about it, there is really no possible way that Schallers could fail, unless the nut got unscrewed somehow and the whole thing disassembled while you were playing (highly unlikely) or the mechanism failed and you flipped your bass upside down while playing and the bass fell out of the U clip (even more unlikely.)
MIA Fender basses come with chrome Schallers standard. Schaller must be doing something right!