They are ALL green iguanas (same exact subspecies) so don't let a pet store try to fool you... Much of the "blue" and "red" actually tends to phase out and dull down over the lifetime of the reptile, so if you are looking for a green iguana with a different color to it, get one from a reputable breeder that will show pics of the parents in their adult phase. I recommend buying captive breds from private breeders anyways.. I recommend checking out TY Park, you can lookup that name (or ty parks reptiles) on facebook.. He is a well known and respected breeder.
The temper is solely based on the individual reptiles personality not the color phase.. And simply put how you raise it too. If you really want a reptile the size of an iguana, the common iguana we all see in stores and peoples home are just ONE of many different actual types of iguanas, I would personally suggest looking into a Cuban iguana.. They are different than green iguanas and cost a bit more too - But you get what you pay for.. they are far better tempered to human interaction. TY Park is a GREAT source to go to for various iguana subspecies he has quite a few different subspecies he breeds.