While claims for better reliability might have been brought up with the new BB designs, real world tests have shown that they are all about as reliable as the next. The biggest difference in that for external BBs, you can often replace just the cartridge bearings and reuse the shells. Square taper BBs can also be had with replaceable bearings (though most are not). Square taper allows adjustment of chainline through different length spindles which is impossible with the other designs. External bearing cranks are the easiest to R&R though.

It really doesn't matter much in the end IMO. I'd base your BB decision on which crank you choose, not the other way around.