The Schwinn is a 1988, for sure. And it's the better bike IMO (I've owned both of these bike in these vintages, but the Miyata is gone; the Schwinn is still around). The rust is a bit worrisome, but neither of these bikes are show pieces, so ya pays yer money; ya takes yer chances. If I was to be looking closely at the Schwinn, I'd bring along the tools to take off that kickstand to make sure no grievous harm has been done by it, then maybe put it back on after buying the bike.

I'm not an upright bars kinda guy at all, and you should note the shifters on the Schwinn are not original to the bike, but if they are SIS Shimano with the correct number of clicks, they should work just fine. They are not likely indexed shifters; the ones on the Miyata are not indexed, but they are original to the bike. (Those are very good friction shifters). The original rack on the Miyata is a big plus in its favor. The brakes (brake calipers) on both bikes are all original; the Miyata seems to have the original pads up front and replacements on back. The pads are just adjusted a little bit wrong is why it looks funny; that's an easy fix. Might want to replace them anyway because they are likely old and hard and don't work as well as new ones would.

If you have short legs for your height, the Schwinn may indeed be a more comfortable fit.