I have thought quite a lot about it, actually, and the ideal boat would be 48-50 ft (52 at the most). I wouldn't go down to 40, because I don´t want to make up the bed every night. It would be a cruiser or a semitrad, as we mostly will be two on the boat, and that would give us more room for both of us when cruising. As to reverse or traditional lay out, I reserve judgement. Reverse layout looks nice, because it gives easier contact between the one at the helm and a person inside the boat. But I haven´t tried it. As to the big question, cassettes seems more flexible, so I would prefer that, but I don´t think that should be the most important deciding factor.
But the most important aspect for me is to get a boat in good working condition, which doesn´t need a lot of repairs, overplating, TLC, etc in the overseeable future. I do not want a project. And the engine must look nice and clean.
And I have searched this forum a lot to try and learn, and there is so many people who says that they end up with a boat quite different from their initial requirement. So i try not to narrow my searches to much. I might seem a bit undecided (or quite a lot, some may say), but I am actually starting coming to grips with this. I hope.... ;)