I am just learning to play slide, and can offer a newbie perspective on guitar selection. I am taking lessons from a teacher who plays slide on both an acoustic Taylor and a wooden National resonator. He makes both sound great, but different of course. I started with a plywood topped Fender acoustic that I paid 100 bucks for at a thrift shop. It actually works pretty well. The Ovation electric acoustic I have would not work at all; the action was excessively low. Then I came across a baby Taylor. That action was not acceptable either, very low, but I liked the smaller body size and general low down simple looks of the guitar. With all these, I was hitting the frets when I mashed down, though less so on the plywood top Fender. Again, my technique is like a 15 year olds driving skill, scary bad. Then I discovered what has been the light bulb going off in my head revelation about playing acoustic slide. Take what you got and work on the action. After raising the action, the baby Taylor with a 4 inch body and a thin neck is a dream for me to play on. Instead of making time to practice, I just pick the thing up at every chance. I do not think there is any magic in the Taylor; just I finely got the action right. So the new kids advice is find something that is either cheep, or calls out to you, then spend some time learning to either shim an existing saddle, or file down a blank. Use an open tuning and a heavy slide and play until your fingers hurt.