For a first keyboard, I think it really depends. If you've tried other mechanical keyboards, and kind of know what to expect from a mechanical board, Topre is a great option. My HHKB is my favorite board, and I love my 87U. Having said that, if you've never tried or used much of another mech board, Topre may or may not be a good first choice. Topres are like rubber dome, perfected. They feel fantastic... smooth yet tactile, awesome sound, etc., but (in my opinion at least) if you want to get the "mechanical" experience out of your first board, the Topre probably isn't the best choice. While the quality typing experience is night and day over rubber dome to me, several of my friends who have tried my Topre boards have come away with "it's nice and all, but cost HOW MUCH???" As apposed to them trying my blues or browns and noticing difference enough that they understand the massive difference in board design.
All that's to say that with all the talk of how awesome Topre is (and rightfully so), if it's your first mech board, it would be easy to build it up as this holy experience waiting to happen, and to be disappointed when you try the board for the first time. It's totally a preference call, and Topre is definitely worth it IMO, but if you've not tried one before, and are looking to get into collecting, rather than getting just one awesome board to use, then I might start with a different switch.