You would ask me a hard question like that. To me, it doesn't matter. I have used both in desktops and I see very little difference. Yes, benchmarks can show some margins of which is the better chip, but when I am gaming, I don't notice the difference. And this is with FPS as well as RPG games. It matters more to me at which one is in the most powerful system at the time I am buying. If the AMD had the same equivalent system out when I bought the EX7, I may have gone the AMD route as I do see good reviews with them. However, I am not set on either one. Someone else may be better to answer this question for you.
Graphics on the other hand does matter to me. The more memory I can nail into a card, the happier I am. Since a lot of games are coming out with max requirements or suggested recommendations of 128mb... then I need more than that. I would definitely go with a 256mb version.
Don't get me wrong, games will play with the 128mb, but if they are already being released now using that much, how long before you will need more? And does that coincide with the replacement of your laptop. For me, I just happened to get two in a row, but that is a rare case. My last one was three years in between. This one here will be about the same. Need to pimp my ride now, not my lappie.
Hope this helps.