A Hard Decision Indeed

So, I open this question up to Tumblr. 

For the entire time I have written Dark Soldier, the riders of Jevruun (a mountain city in the coldest regions of Vaelora), have always ridden moose. But I am considering changing that for the final draft sent to agents. I now think perhaps it is better that they ride caribou or reindeer. But moose are also very large and intimidating to those they would do battle with. And just imagining that is cool.

So I open this question up to those in Alaska, Russia, and any cold regions where you ride something other than a horse regularly. 

What would be a better steed for Jevruunites, a caribou/reindeer or a moose?