If talking is important I'd suggest getting a bird that already talks. Sounds like the older grey you mentioned would be a good choice, if the bird likes you & is what you want. I don't own a grey but have heard lots of good things about them.
But as I say, if talking is the issue, make sure the bird you get already talks, regardless of species, so you won't be disappointed. This is actually a good opportunity for you to get what you want and do a good deed too. If you want a specific trait (like trained speech) you're better off getting an older bird, so you can be sure of getting that ability. Birds that already talk *well* can learn more words all their lives, too. If they already enjoy talking, they will continue & could easily expand their vocabulary if encouraged. So I'd suggest a rehomed bird with a good temperment who takes a liking to you.
It's of the utmost importance that the bird likes & "chooses" you, when you get an older rehomed bird, though. So you really have to be careful about that aspect. If you Do get a rehomed bird who likes you you'll have a friend for life and a Great pet! I have mostly rehomes & they are wonderful! So please consider a "2nd hand" bird. There are lots of advantages, in addition to making sure you're getting the traits you want.
I have 2 macaws & 4 amazons. All "talk" a little bit. (None are nearly as oriented to speaking "human" as the greys I've heard about though.) Amazons are better talkers IME than macaws, but of course there are individual birds that are exceptions. The one Ekkie I've spent time around could talk, and was very vocal, but mostly imitated many different sounds (cell phones, car alarms, you name it) rather than talking with comprehension but he could say a few phrases. Not as smart as any of the amazons I've known though. JMO
If you want communication as opposed to imitation I'd suggest sticking with the smartest of the birds. IMO that would be greys & amazons. There are A Lot of older amazons available for rehoming. Mostly males, though, which often means hormonal issues - but not always. If you get an older male zon who adores you that can be a good thing. (Read "The Parrot Who Owns Me" to see how male zons can be when they're much older, if you get lucky and are able to develop a special relationship!)
I hope you're able to find the talking dream bird you want.

Like I say, there are lots of Amazons out there up for rehoming - I hope you'll check some of them out to see if they are what you want.