I would also be on the hunt for a pre-MTD Troy Bilt. I've owned front tine tillers, rear tine tillers, and this spring came across a basket case '84 Troy Bilt Horse with the Briggs I/C 8hp engine. One engine rebuild later, and that thing is hands down the best tiller I've ever owned. It's not going anywhere for a long, long, time.
In my simple world rear tine > front tine, and forward rotating tine > counter rotating tine. My mom has a post - MTD Troy Bilt horse with the counter rotating tine and I can't stand it. Ironically enough, I've been given the job of selling it this spring when gardening season starts.