I haven't decided on one vs. the other yet. Any recommendations about which makes more sense? I don't expect to take a ski vacation more than once every year or two, so whichever one is easier to grasp quickly would probably be ideal.
Whichever is easiest to grasp quickly depends on your background and intent.
For exercise, skating is more rigorous. It'll get your heart rate up in a hurry in the smallest hills. At least in the beginning before you get the techniques down, it feels like sprinting! THE WHOLE TIME!!!
People who's done a lot of ice skating can get the hang of skating skis very quickly. But since you asked, I suppose you're not a proficient ice skater? There's also a theory strong downhill skiers have an edge on skating ski, I'm not sure I buy that.
Once you can get going smoothly, the rush of speed on a skating ski can not be underestimated! It has the highest of "highs" I get in all sports I tried! Super addictive!!!
Classic, on the other hand, is a bit more forgiving at the beginning. You can simply walk on the skis for a while if you get tired, in between actually "skiing": i.e. kick and glide. And as you get better, you can gliiiiiideeee a long way for each kick, which is really sweet.
Downhill is what "gets" a lot of occasional x-c skiers. With the heel free, control is a bit sketchy. A lot of people totally freak out on downhills. And a lot of the so-called "lessons" spend all the time on downhill control. I'm not a big fan of that approach. Their client never really got into the "skiing" technique. They're just walking around on skis. They might as well walk around on snowshoes! Best to separate the two and focus on each for a day, or at least half a day on each aspect.
A lot of people x-c ski just to "get to" places they can't get to without skis. For that, classic would be the easiest and most appropriate. It also lets you go off the groom tracks easily. Majority of first-timers start on classic, for that's what they want to do.
If you don't get to ski a lot, and don't have a strong ice skating background, classic would be the easier choice.