Hi, Casper's mama and welcome to the forum. I am glad you changed your mind about getting another IRN because they are really stressed out when they don't have another bird to interact with (they are more aviary than companion). Amazons are great parrots BUT you need to be extra vigilant in the solar schedule and the diet because an overly hormonal male can be quite dangerous and, if you don't feed them right, they all end up dying before their time from liver and/or kidney failure so, if there won't be anybody home during the day in your household so the solar schedule can be kept, I would recommend you do not get an amazon. As to what species.... well, in all honesty, of the species I've had (yellow nape, yellow crown, lilac crown, redlored, bluefront, orangewinged) the only thing I have noticed is that some speak better than others (all the yellow heads do) and that the females are the talkers. I had a male yellow nape that did vocalize in such a way that, when you heard him from afar, sounded just like a person but the sounds did not make actual words - they just sounded like words
What I can tell you is that they LOVE music and singing, especially 'opera style' -Mami, an old YCA, actually asks for music ("Tralala? Tralala?") so she can sing along (VERY badly, mind you, as she seems to be completely tone deaf - but she loves it). But, aside from their talking ability, I truly cannot tell you of any 'real' difference between the species except that the bluefronts seem to be a bit more noisy than the others.
Now, amazons are not cuddlers and they are not family pets. No parrot really is. I have found that the GCCs (and other similar small pyrrhuras), cockatoos and macaws are more patient than other species in terms of being able to interact with other members of the family without biting them -some of them even enjoy other people's attention (the cockatoos especially because they all have a wide 'ham' streak in them) but they all love one person and one person alone. It's the way nature made them (they are monogamous and mate for life) so, although they can be friendly with people they know and trust, their devotion will always be reserved for their chosen one (and the operative word here is 'their' as they are the ones that choose the person). And I have never known of a single amazon that is a real cuddler. They love spending time with you, riding your shoulder, preening your hair, talking, roaming, exploring, chewing (BIG time this time of the year!) etc. but cuddling and a lot of touching is not their cup of tea. Cockatoos and GCCs are cuddlers while amazons are actually quite independent and the one thing that makes them really happy is having another amazon to love.
I love amazons - they are such easy birds to keep happy and healthy... they are GREAT eaters and bathers, they only fly when they have no other choice (perch potatoes through and through and, although this is not something that makes a difference to me, it does to my husband who is not too keen on large birds flying over his head), they are not screamers or prone to plucking (not that plucking is unheard of, mind you, but it takes a lot of neglect and abuse for them to resort to it) and, give them a strict solar schedule, the right diet, another amazon and stuff to chew and they are happy puppies!