WHOAH. First of all, have you ever had a bird before? And how much research have you already done? 'Cause Senegals and Amazons are two COMPLETELY different birds in regards to temperament and noise level.
Amazons are generally decent talkers and not afraid to show off their vocal abilities, but they are seriously LOUD. All birds will go through a hormonal stage, but Amazons have a breeding season each year where they get more aggressive and possessive. I really wouldn't reccommend them for a first-time bird owner. Besides that, Amazons can potentially live up to 70 years or more! That's a huge commitment.
Senegals aren't really well known talkers, but they generally pick up a few words and sounds in their lifetime. They're much quieter, and more independant, but they can be nippy. Senegals tend to be one person birds and can develop phobias fairly easily. HOWEVER, they are far more suited to first-time owners than an Amazon. It's all in how you socialize them. They're very smart and can learn TONS of tricks. Just look up Kili on YouTube. Senegals aren't quite as long lived as Amazons... I believe the average life span for Senegals is about 30 to 40 years, but that's still no small commitment.
To be totally honest, a budgie might just be the best starting point. They're small, affordable, very docile and can be excellent talkers! I believe it's a budgie who holds the record for the largest vocabulary with over 1700 words and phrases. The only thing to keep in mind is that budgies have a reaction time that's 7 times faster than humans, which results in their talking being very fast and high pitched. You have to teach them in such a way that it isn't as affected by their 'budgie accent', by saying what you want them to say much slower than you normally would, but still in a dramatic way or they won't pick it up. Parrots thrive on drama!
Really though, talking ability is never a good reason to buy a bird. You might want to do TONS more research and seriously consider whether you're up for parrot ownership. If you still are, and you still want a larger bird, but are concerned about aggression issues, I would suggest rehoming an adult bird. Adult birds aren't as likely to undergo personality changes as babies, so what you see is what you get. Find an adult bird with a gentle personality that you really connect with and give it a new home.