[Closed] Need help choosing a rear rack for an old Rockhopper

I have a Rockhopper (90's vintage?) that I have wanted to get a rack for. I had picked-up a Blackburn TR-1, but haven't installed it yet. I had been originally considering an MTN-1 or a Topeak Explorer. Not having had the opportunity to see (in person) any of these racks before and thinking that I may have needed it soon, the sales person sold me what he had, a TR-1. Since I no longer have the urgency, I thought I'd try to get some unbiased recommendations before I use what I bought. I called Blackburn's support line, but they couldn't offer me anything meaningful (not even dimensions) to compare the MTN-1 with the TR-1. I do know that Topeak's benefit is that it supports a special mounting system (MTX?) for bags, but that aside, what are the strengths and weaknesses of these racks so that I can better make a descision? Should I consider something else for general occasional rack use?