if you're going for a complete city (i.e. coruscant) the biome probably isn't really that relevant, as you'll be covering it all up anyway. on the other hand that is lots of work.
desert is relatively easy, you can see a build from far off, could look good.
jungle: futuristic towers rising up out of all those very saturated greens, could look brilliant. however, you need to build tall, jungle trees are over 30 blocks tall, and you'd want the towers rising up above them. also a pain to get started in as you have to clear the area first.