my bike came with an ISIS bb. I used to like ISIS but now I think it's bollocks - as you know, the axle is pretty fat, so the BB has to have smaller bearings... which only last about 6 months before self-destruction.
replacement bearings are expensive (£18) and cups are £15, whereas a whole new BB including axle, cups + bearings costs just £25. the bearings would be a pain in the arse to replace anyway.
and the tool to remove the cups doesnt go in very deep, so there's a risk of it slipping and wrecking the teeth on the aluminium cups...
the raceface isis tool in particular is shite as you cannot use a big spanner on it, you have to use a square ratchet. so there's no way of holidng it into the bike (you could use a qr skewer to hold it in and a spanner to turn it if the outside of the tool was hexagonal)
I think open bearings on a square taper axle are the best - regular cleaning and greasing should ensure that the bearings last ages. And theyre cheap as fuck to replace.
I think your arguement is flawed. Regular cleaning of a courier bike forget it. I haven't cleaned my bike since the great flood of 1953. Ride it, brake it and replace it.
cartridge all the way- fit and forget... till it plays up, then fit forget and start all over again. open cups, miche, campy ones with that fit using the cassette remover are all more trouble than they're worth- don't even get me started on the demented way that royce bbs used to fit. the fatter axle on the isis technically means that the load is spread over a larger area and *should* last longer, same goes for external bb systems. have had mixed experiences working on them tho.