I would definitely recommend a cockatiel. They are common & inexpensive, but can whistle and many talk in a chirpy high voice. I had two, and both had great personalities, were both very tame, did tricks, and could say a few phrases. One of them whistled more than actually 'said' but you could hear the words in his whistle, if that makes sense.
IMO (I've had parakeets, cockatiels, and a few types of parrots) cockatiels are the friendliest and happiest-the parrots can be smarter/better talkers but they don't have the sunniest dispositions all the time. Cockatiels do-they are happy little birds who love their owners, and are more likely to be hand tame/talk than parakeets.
Try to get a male, they can be more affectionate and better talkers (in cockatiels head color makes them easier to sex than many birds) and get a hand-raised young one for best results. If you contact a local bird club you can probably find a breeder with babies from this spring-here hand raised ones go from about $30-$70 depending on the color.