Your best bet is probably the Early and Mid 2009 models. There's not much of a difference between them. But, you don't have the overheating issues of the Radeon X1600 Mobility on the Early and Late 2006; you don't have the inevitably failing GeForce 8600 GT issues of the 2007 and 2008; you don't have the GPU issues on the 2010; nor the inevitably failing issues of the Radeon HD 6000 series on the Early 2011 and Late 2011. So, yeah, 2009 is probably your safest bet. It's a Penryn Core 2 Duo, but you have the NVIDIA GeForce 9400M and GeForce 9600M GT and you have manual control over which one is running when (compared to the auto-switching you have on 15", 16", and 17" MacBook Pros from 2010 through 2019).