To be honest I only had a quick look at some of the other operators.
My parents had looked it in all so thoroughly when they went 2 years beforehand, that I used their holiday as a basis. We had relatives that also went with Canterbury and weren't impressed.
Esprit included all the proper clothes gloves etc in the holiday which not all of them do.
Saariselka is cold but they do also go to Rovenimi (not sure of spelling). Our friends went there with Esprit and loved it. It is more commercialised than Saariselka and I think more touristy.
The cold is an issue but we had really young children on our trip. If it is too cold it will mean things like the skidoo trip is not suitable for them as they go in a trailer behind so the wind chill factor is horrendous for them. We had children crying with cold and some of the mums sat with them in the trailer and couldn't believe how much it affected you. Whereas on the skidoos you were fine as you had heated handlebars etc and a full visor helmut (although it did mist up). That is an optional extra though so you can choose not to do it.
When we did the activity day there was a hut you could go into for warm berry juice and cookies and there was also a restaurant where you could stay in the warm. So it is possible to be in and out of the cold.
If you do go, take loads of layers as well as the clothes they give you. We all had thin wool gloves on underneath the ones they gave us, as well as thermals, tops, extra socks etc. They give you the gloves and boots larger than normal to allow for the extra clothes. Bit of a pain layering up in the morning but worth it. We also took our own hats although they did give us some and your all in ones had hoods on.
I must admit it was freezing when we were there but we didn't really feel it most of the time. Your fingers and faces are the worst so balaclavas for the children are great. I had a scarf pulled up over my face and it still froze up occasionally during the day thanks to me breathing. lol.
It is worth it though when you do things like the husky ride and play ice hockey.
We were lucky as well in that the hotel we stayed in had a swimming pool, so we used to come back and relax in that before dinner.
One thing- they are very fond of small frankfurter sausages over there as a lot of the food has to be imported. We had them for every meal (buffet style) including Christmas dinner.