Good comments Wes. I have sailed on all the luxury lines - not. In fact, the two I have NOT been on recently are Regent and Seabourn. I just haven't gotten around to it, nor have I been invited onboard as a member of the cruise press as most other cruiise lines do - which I find very odd.
I think one ever-riding factor is that newness seems to have a lot to do with these polls. People seem to like new ships. I like the Silver Spirit. I also think this is why Seabourn has risen in the these polls.
I doubt that if Seabourn still had just the three smaller ships that people would be nearly so excited about the line still.
Crystal, however, is hard to beat for sheer indulgence. I would take a Crystal cruise for many reasons right now, entertainment, activities and food among them, over the smaller lux ships.
If Regent is indeed slipping as Eric suggests, I suspect it has more to do with age of the ships than anything else, but I don't know that to be true. (I would like to try a Regent cruise and see how I like it).
I can tell you my Silversea (Silver Wind) cruise to Egypt was spectacular in every way possible. I personally don't really see how Seabourn having so many 7-day cruises works for them, but apparently it does. They must be very nice ships - but I find it hard to justify spending time & money flying to Europe for a 7-day cruise.
I do believe, like Eric, that I don't trust the polls much, either. They each individually seem to be dominated by the same lines year after year - so what does that tell you? So, I am reserving my adoration for Seabourn for after I see the ships. Same with Regent. Polls do not affect me much either.
I have been just fine with only Crystal and Silversea for the last few years - no complaints. (oh, and also lots of premium and deluxe line cruises)