Mountains are annoying to build on unless you get inspiration to build a column supported building. Other buildings look ugly. They're also annoying to travel on.
Build between the valleys, maybe with a large structure on top in the center. It could work. Or on the outskirts of one, just slightly going in, like in the previous vincent world (nut summerhold, the one after)
I don't think the current map has too much water, I mean, you can find huge continents that are for the most part unoccupied if you look hard enough. Building a base under the water is also kind of a fun challenge, thats what I first did. Easily able to get to spawn from it, and completely hidden. Power was a bit challenging though, since no solar. Anyway, for a new spawn, I would also vote mountains, they look sweet and if you know how to build on/around them you can make a bad ass looking town.
You can use nucelar reactors and water gens. A hidden udnerwater research facility sounds awesome, too.
Water gens? You mean lagmills? You know those are the #1 most serverside and FPS lag generators (after players ).
Really? That bad? Then, where else would you get power from in underwater bases aside from nukes, which blow up, and coal/lava, which need to be fed?
I think jungles would be nice, since I always wanted a few ocelots and wolfs. But mincraft PE dosen't allow that to happen......(-_- )