Hi. My 4year old grandson has asked for transformers for Christmas. Phew, when I went to look I just didn't know where to begin. Which are the easiest to transform, which have the most play value for a 4yr.old. I think some of them are maybe too young for him, but most seem rather too old.I would like something that he can play with for some time to come, but it isdifficult to know these things from the package.Finally where is the best place to go for them? Sorry - lots of questions but I hope to get lots of answers! Thank you in advance, Rosie