I too am deciding between OSU and several other schools, and am also leaning towards OSU. However, I dont know anything about Maryland. I am sure it too is a fine school and if you do well at either one you can do whatever you want.
At OSU you can pay instate tuition after your first year, so that is a serious consideration. Some things I liked about OSU, very good reputation, good match list, lots of research going on, huge hospital with lots of opprtunity to get invloved with whatever interests you. The students I met that day also seemed very down to earth and sociable, though thats always hard to know for sure because you dont really meet that many. I also liked their curriculum beacuse they only have 3 hours of lecture a day and not too many afternoon small group things. But I prefer sort of independent learning, so I like a curriculum with a lot of free time. Also, if you don't need a huge metropolis or sunny weather everyday Columbus seems like a pretty fun place to spend four years. It is a real city but also has sort of a college feel which is kind of fun.
