If you want cheap and durable get a square taper bottom bracket. Even the lower end ones will last forever. A Shimano UN55 can be bought for about 20 bucks and will last decades. I'm pretty sure that's what I have on my 1x1 and that thing has seen a lot of miles and crappy conditions. If you want something fancier, buy a Phil Wood and then you can even replace the bearings in the unlikely event they fail (the Phil Wood on my Fatback has been on for eight years and thousands of miles in conditions including mud, slush, even volcanic ash mixed with the snow. Thing still spins like the first day)

External BB usually fail earlier than square taper. But they give you the option to use modern cranks. The selection for square taper is getting limited.