This is almost perfect... but I turn him a bit where I am move in line with that pillar on the bosses right. (one-two tiles down from the fire animation on that picture)
Printable View
IMHO it really doesn't matter where you place him, if you step into his rear-area the tailswipe will trigger. Just step out and wait for 1 second and then move back in.
It is however easier for people who can't think on their feet to have him butt against the wall.
For the folks saying "I do this all the time, tank anywhere, this is easy": If you've got a model that works for you and your friends, and you're having fun, keep at it. This post wasn't written with you in mind. :)
I'm a healer, and I try to teach folks. I stick it out with parties that are new or parties that are under-geared; my gear and some light instruction can help compensate for that. I just figure there's no good reason to keep sticking the dragon's rear out where new-ish players are likely to eat Concussion effects. The tail swipe is something any tank can fix. It doesn't cost any time, reduces risk, and seems like a no-brainer.
Thanks for all the constructive replies!
Note: I really like the "point his butt at northeast corner 4" approach. My FC's PLD uses a similar location. The 'optimal' graphic I linked was the first one I found that illustrated a better facing. (I was posting from work, and my msPaint skills are notoriously bad.)
The problem is tanking him tail against the wall is that targeting can be skewed for ranged DPS as well as the adds potentially targeting the Tank.
I prefer the tank holds him tail to the middle, on the far side of the right pillar. this allows for melee DPS to continue DPSing during catastrophe cast. Seriously, if you are being hit by tail swipes, you are out of position, no matter what class you are playing. If the tank stands in the center of the wall at right side pillar he doesnt have to move for catastrophe, he wont be hit by adds, and the tail swipe will be irrelevant for anyone who isn't running around the middle of the area like a fool.
The position you refer to as "worse" is one of the most common positions lol.
Your so called best position is not the best btw. I don't have any screenshot available right now but yeah...the best position is not that.
edit: Just saw it. Yeah the screenshot Saeri posted is the best position for him.