K.M.
We really thought about this as well, but the decision ended up being made for us because our son were given these as gifts. One friend gave our son a VTech product. (I can't remember the name, but is was a laptop style.) The screen is too small and the games are a waste of time. It ends up being a noisy toy that he uses when he wants to 'pretend' to be like mom and dad.
Another friend bought my son a Leapster. This has greater longevity because you can buy different cartridges. (Warning - they are not cheap! Anywhere between $15-23.) But he usually gets one for his birthday. The only thing I don't like is most of the cartridges are based on TV/Disney characters.
Good luck,
K.