We tried all of those dolls before we caved in and bought Hannah an AG. It really depends on how well you think your child will take care of it. The quality is not the same, the hair is very different and you can tell. Hannah got her AG doll on her 9th birthday. Hers is well taken care of, but I do think she was on the end of the spectrum for playing with her. I think if we had gotten her a year or two sooner she would have enjoyed her much more. Hers is in A+ shape though. She didn't want a real one until she really got into the books. Allie is 4 and very destructive, so we're going to wait a bit until she can take care of one before she gets it.
I think it all depends on the child. If your 5 year old will take care of it, it will be a great investment and all of the stories will probably motivate her to read more, but if she's not able to take care of it it might be a waste