Lexington Market is quite sketchy, unfortunately. Charles Village is right near the Hopkins Homewood campus (shuttle), and is reasonably nice. If you want to live on the Metro line, you could live all the way out in Owings Mills, but I'd imagine that would be quite a commute. I've actually never riddent the Baltimore Metro in 25 years here. It only has one line, so if you're not going to Owings Mills or Hopkins, it's kind of useless.