I've only had 4 clutches so my experience is limited but I can tell you that babies go through many stages before they develop their own definite personality. I would expect them to be a good 4 or 5 months old before the breeder can tell you who is going to prefer a lively household compared to who might like a bit less action. But, regardless which one you select the way YOU handle the bird, especially the first couple months you have him, will make a huge difference in how it reacts to you.
There is a stage where any youngster will bite if you put your hand in its cage. You can actually teach it to bite by doing this, which of course you don't want to do. Right after they fledge, which you of course won't witness as you will not get your baby until it is fully weaned at about 5 or 6 month most likely, the youngsters will strike at any hand coming at them, even their hand feeder. So someone observing them might think that one or the other was more aggressive since instead of taking a treat nicely at say 12 or 13 weeks, the chick tries to bite at the hand. But what would be happening is the natural instinct of a young bird to strike something approaching them. Soon they get beyond this stage and if they have not been pestered to death, will begin approaching people on their own. Most Eclectus are very nice birds who for the most part, tame themselves.
Of course there are some subtle differences in each individuals, but IMO and IME whichever bird comes to live with you will do just fine and learn your ways as you learn his.
They continue to change as they mature and by the time you have a 4 or 5 year old bird you may think back and wonder if it is the same fellow you brought home!
On a side note, if you have an experienced breeder s/he will ask you many questions, trying to determine what type of home you have (noisy kids, retired person, yippy dogs, anxious partner) and *try* to match the bird to your personality and lifestyle. Sometimes a breeder may even tell you that they are not sure the species they breed would be suited to your home.
Like Jenny said, Eclectus don't care to much about receiving scritches or being petted. The reason is because of the feather structure on their head and neck feathers, compared to other parrots. These are the areas that a bird cannot reach too well on itself, other than a scratch with their toenail or rubbing against something, so most parrots accept and enjoy help removing the sheaths on pin feathers growing in these areas -- scritches. Well, Eclectus feathers in these areas are almost hairlike with sheaths that easily fall off on their own, with maybe an occasional foot scratching to speed things up. I do have a handicapped young bird who cannot move his legs and he does accept a bit of touching in that area from me when he has lots of pin feathers. You will rarely see an Eclectus grooming another Eclectus other than a parent with a very young chick, but some Eclectus can be "taught" to groom other species by the other species.
Regarding cuddling, I highly discourage it. Do some reading online about Eclectus, especially the pet males, and you'll see that owners become quite frustrated trying to discourage mating behavior directed at themselves, from birds they have cuddled with over the years.
I would also pick the one that is more inquisitive of his surroundings. 
