We were thinking of going this year but have now decided to wait until next year as we're in the process of moving house.
I read literally hundereds of reviews. The canterbury ones were very mixed. What I noticed was that they had excellent reviews until about 2yrs ago then they become very mixed with some very poor ones. It sounded to me as if they used to be the best in the business but have now let themselves down a bit.
Bear in mind that this is all opinion though as I haven't actually been yet. Also read a review from a rep who had worked for them saying they used to be great but since recession their customer care had gone down hill. However, of course you have no way of knowing why this rep has left so cannot take it as absolute truth. Having said that, together with the reviews it was enough to put me off. So with regards Canterbury, just check dates on all reviews.
Emagine are (I think) a smaller more specialised company. Couldn't find many reviews but everything I found was good. So from what I read, a safe bet but probably the most expensive option I came across.
Also looked at First Choice. I was least impressed by them. Lots of their hotels were actually city centre based so no real atmosphere. Lots of reviewers saying how disappointed they were with the Santa meeting. Apparently he comes around during dinner handing out random pressies. So no finding his house in the woods which others offer.
Transun looked good to me but very mixed reviews again.
Also looked at Esprit. Offered private santa meeting like Canterbury, Emagine and Transun. Very good price. Their log cabins appealed because just 4min walk to hotel and because hotel had a swimming pool and we wanted something to do in the late afternoons as its dark by 3pm. Downside is their resort is quite far north so cold. But they fly to a closer airport so just 20min transfer. I couldn't find any bad reviews about them either which was reassuring. Lots of recommendations for them on here too. Obv they're a ski company but I think their Lapland hols have a separate website called santaslapland (or something similar) Google esprit lapland.
If we had booked I'd have gone for Esprit I think but before booking next year I'll check the most recent reviews. I have 3kids so not a cheap hol so want to get it right. Next year the youngest will be 4 so probably better for her in terms of the cold.
Good luck.