I always go with OEM power supplies. It's too important to mess around with, even if the numbers match up. Do they really match up...ya know?
Now I'm going to go against what I just said....and it has to do with the Genesis and 32X power supplies. There's a site that makes ultimate power supplies. Normally, I wouldn't care. Just stick with OEM, but, they also combine power supplies... No need to have a separate power supply for your Genesis, 32X and Sega CD. It's all combined into one kickass power supply. They're not cheap, but for me, eliminating power supplies was key. And in the process, I got hi-tech electronics, rather than 30 year old stuff. Here's the site, if you or anyone else is interested: http://www.retrogamecave.com/shop/4577155950