I like 10s better than 25s.
1. With 10 people you normally have a tighter group.
You know each other better, and you have to trust more on each other to do the job. In 25s you always get sub groups. This is not even my experience only, there has actually been research into this stuff and once a group gets to big, it will automatically split into smaller groups.
2. I find deafeating a boss with less people a lot more epic.
Think about it...I defeated all those big dragons and baddies with only 10 people, other groups needed 25. Bah weakos, had to pull in all their friends to be able to beat da boss.
3. With only 10 people there are less spell effects and I actually get to see more of the fight.
When I ran 25s I saw very little of the fight itself, the spell effects were overwhelming. I get this with LFR already and there you don't even have to focus much.
4. With 10 people each person has more accountability per person.
My experience in 25s is that more people can screw up. Actually, it's a fact that with 25s more people can screw up because you get 3 battle rezzes, and you even get more shaman logically that can self-rez.
5. Healing is a lot more intense in a 10man raid.
With 25 people you have 5 or 6 healers covering the raid. You have a certain role, you do your role and you don't often move away from doing your role. In 10s you sort of have to be able to do everything. In current content the only boss we have somewhat strict healing divide on is Garalon, and even there we have to keep an eye on all targets and not just on the ones our focus is on.
6. Organization is less intense in 10s.
What can I say I am a control freak...or wait, think positive...a natural leader. When I see a situation that needs organization and structure I tend to step forward and take over. Not in a mean way, but it naturally happens often. I know what I'm doing and when there is not a strong lead in a group I take over.
This leads to me always leading something in a 25. In our 10s people lead themselves. I do some organizational stuff, like copy/paste the calendar invite, but the rest gets itself arranged.
I do have to say that I am incredibly lucky with the base of our 10man group. We've had people rotating in and out, but the base group is strong and stable, for which I am very thankful.
There you go, six strong reasons for me to like 10s better. So the fact that Blizzard feels that 10s are worth less than 25s, is to me another disappointment to the game.
Bit of a shame...I was discussing with Thror yesterday. And while this whole loot change is on its own not even all that big of a deal. MoP has few things in it that not have a bad aftertaste for me.
I hated Cataclysm with a passion, but I play less during MoP...but hey, that might just be the next blog post.