I've been to both and both are good.
My preference is for the Picturedome as it's just got a lot more character. It feels old fashioned and has a slightly unusual layout in that there's tiers so if you're on the floor it feels quite enclosed. Holmfirth is a really nice place as well for a few few beers. Saw the Inspiral Carpets there and it was brilliant. One thing to bear in mind if you're thinking of going over in a few weeks is that if it snows then you might have a few problems or have to do a big detour.
The Met is fine, good venue but just doesn't have the character. It's all personal preference of course though!