I prefer 25s. Guild fell apart and went to 10s. Fell apart again and went to SWTOR. Looking for a 25 man guild now.
I wholeheartedly disagree with the title. I was a part of two 25 man raiding guilds this tier, both which fell apart (one started at the end of WoTLK, one was around since vanilla) due to lack of quality recruitment. It really has a LOT to do with people preferring 10 mans. "Why apply to this 25 man guild when I can do 10 mans with the same reward and less hassle?" We had the natural attrition, (which was a lot more then in times past due to the game getting stale) but it was harder and harder to replace those longtime raiders that quit, because the quality AND quantity of applicants was so low. We hit recruitment hard, but still weren't getting enough bites. (This is a guild that raided 3 days a week and finished T11 13/13 H with a world top 500/US top 150 rank, so it wasn't some mediocre guild that couldn't recruit because they were mediocre)
There were a lot of people who predicted, when the fusing of the lockouts change was announced, that it would slowly kill off 25 mans, because the incentives to do 25s weren't enough. (majority of those incentives don't even remain for whatever reason. Remember 25 mans were supposed to get more loot per person, more VP, and more gold?) I myself thought it was a change that wouldn't make it to live because it was so stupid (IMO).