With regard to the 2012 MacBook Pros (MBPs), I wasn't aware of the GPU issue. However, I have two of them, got both of them used and since they were cheap enough that wasn't a problem. The things I like about the 2012 MBPs is they have USB 3.0, the hard drive is easily upgrade-able by the consumer to a SSD, and the memory is likewise easily upgrade-able. With the prices of SSDs and memory as cheap as they are it really makes it easy to upgrade.
The advantage of the SSD is it is so much faster (that's a given), but it also consumes less power so if running without a connection to the Mag Safe the computer would run longer. Another plus is, should the computer be bumped while the SSD is running there wouldn't be the problem as compared to a hard drive. The memory can be really boosted up from what was in the original machine. These two upgrades, and the fact one can replace the battery when it needs to be, are the three major pluses for the 2012 MBP.
For starters, check the Other World Computing web pages for upgrades. Note that 2013 and later models and are not consumer upgrade-able!
Anyway, that's my biased opinion.
P.S. If you buy used, be sure to check the speakers (not blown out) and that the USB ports (and others) are fully functional. I'd also recommend meeting the seller at the Apple Store genius bar (with an appointment) and having the genius person give it a thorough check. They are set up to do that. Also check the administrator account (can be put in your name) and, of course, that it isn't stolen (not as easy).