We are going to hawkstone follies as well this year and also the magical journey thing.
Previously we have done:
Webbs
West Midlands safari park
Several valley
Hartlebury museum
Snow dome
Wonderland at Telford
We didn't like the severn valley that much, but it was freezing and chucking it down which may be why. It felt a bit impersonal and the santa wasn't great.
The santa at wonderland was the best we've seen but it chucked it down then too which made it miserable and we didn't enjoy it very much.
The best overall experience was the snowdome. You don't see santa individually but you go to a santa show and all the children get a chocolate lollipop. You play in the snow / sledge for about 45 mins and then see the show. Ds has loved it both times we have been.
Santa safari at West Midlands safari park was ok but santa was a skinny 20 year old which wasn't great.
Webbs is ok too but not really a full day out, maybe half an hour? And you tend to have to queue even when booked in at a time slot, although in the week it isn't as bad.
The only one we've done more than once is the snowdome.