I just mentioned the PIC, because, well nobody had yet, and its usually one of the first suggestions...
I haven't start on microcontrollers yet, someday perhaps when I come across a project that needs one. Yours, well I'm thinking you are looking to build several of these water dispensors, so it would save you time and money in the long run.
Personally, I think I'm going to start with something like an AVR microcontroller. I did okay with assembly when I programmed on the old computers, and want more than 32 opcodes (PIC). To me, I'd think it would be easier to program, at least have some options.