Low-maintenance bike that performs well?

Other than using stout tires appropriate for the conditions you ride in, there's always going to be a need to clean your bike after riding it in rougher weather... unless you don't care about keeping it for a long time. This can be limited to a light spray of water to flush the grit and mud off the frame, wheels and components, chain relube, keeping the braking surfaces clean of any grit, etc. A heavier bike may be less fragile to ride over bumpy surfaces and that sort of thing, but then, if you live in a mountainous area, it's going to be harder to go up and down the hills.

If you cycle regularly in rain (which means the front wheel will splash grit into the chain,) how do you clean the chain regularly? I haven't commuted regularly in rain or slush, but it seems derailleur bike have a slight edge in this regard because you can use a snap-on chain cleaner. Unless, of course, you get a bike with a chain case, but who makes those with an Alfine or other non-3-speed?

You don't need to do a complete chain cleaning every time you ride in rain or whatever. You may not even need to relube it if you're using an oil-based lube, because it's the lube inside the chain's rollers that count, not what's on the outside. When I spray my bike lightly with a hose on the roof of my apartment building (light spray to avoid getting water into places you don't want it to go), I spray some water on the chain, rings and cogs too, just to remove most of the sprayed on dirt. Then I apply some lube (I use wax-based lubes myself).

In colder weather, I do this inside my apartment, by standing the bike in the bathtub.

A more complete chain cleaning can be done once in a while, a few times a year. With modern bikes, you can't take the chain off unless you have installed a powerlink. If you did, you can break the chain and soak it, or if not, you can use one of those clamp-on gadgets (but this really only provides a more superficial cleaning).

In terms of maintenance, it won't matter much what kind of bike you get unless it's a fixed gear, because they all basically have the same kinds of components, no matter whether it's a mountain bike, a hybrid or a road bike. A bike with internal hub gears will require almost the same maintenance, minus derailleur adjustment.

The lowest maintenance bike ever in modern times was probably the "all steel" Raleigh bikes and similar. They achieved this by using oil lube with lube ports, ordinary bearings and all steel components. The price to pay for this reliability was extremely heavy weight.

Thanks for the answers.

I appreciate that there's no such thing as a 'no maintenance' bike. I do know, however, that my fixed-gear bike (which I don't like riding in icy conditions, and couldn't do the hilly commute with every day) is a lot easier to maintain that my derallieur bikes, and I was wondering whether the Alfine would therefore also be easier. I also have never tried disc brakes, but imagine that these are easier to maintain that traditional brakes...

I find my Avid mechanical disk brakes easy to maintain = less rubbish on them and the rim doesn't wear down. Also because it is not hydraulic it doesn't have leakage or bleeding issues.