Well, I think Grey's get all the kudos due to their talking ability, but I suspect all parrots are quite intelligent. Rowdy is just a conure, but she is one of the smartest animals I've ever met. Her "knowledge" vocabulary is very big even if she doesn't say all these words all the time. The other day, knowing I can't say "dinner" or "veggies", I said something vague like, "I need to get your stuff", and she still knew what I said! And she has said some crazy things when she has felt the need to tell me something.
Had I not been working when I first got her, I probably would have started teaching her colors and shapes and things just because I was so impressed by Alex. Maybe I still will, lol! Although if I want them to say the words, Pete might be the best candidate. At this moment he is proving he can be quite a talker, saying new things all the time, and talking most of the day now.