Depends on the bike, but for basics:
Fenders, racks, dyno hub, hub brakes, lights, bell and a leather saddle.
Some of my bikes came with fenders, some didn't. Only two came with dyno hubs the rest I have converted. For bells I prefer the
Incredibell Duet, lights are usually
B&M from Germany.
I like Carradice and similar bags for many of my bikes. My main hauling panniers are Basil canvas.
Aaron