Good thing you ask. These are our two faves...
Smuggs is our "home away from home" each year. Needless to say, we like the place. We also visited Jay at the end of the season (Easter) when they got hit by over 60" over the 5 days we were there (and it kept coming). We had the best ski vacation there for the money.
If your kids can do pretty much anything, either place would be great. Just note that the rating system is a bit tougher at Smuggs. Here is a short summary of comparison IMHO FWIW:
Groomers - Smuggs is far better at any level and has much more to choose from. Groomers have much more characteristics at Smuggs.
Trees - They both have tons of trees (yeah, Smuggs don't advertise their tree like Jay does but believe me they are there). Fun factor is about the same for both. Just be aware that trees in Northern VT is not the same as the ones in Central/Western NY. If you expect them to be as gentle as the ones we have here, you're in for a big surprise. Jay has a better variety for different levels (many more designated as beginners or intermediate) and probably has a few more than Smuggs. Smuggs is much more challenging in general (some of their blues can make you teeth grind if you're not used to them). The green/blue glades at Jay are a lot of fun
Pow - Jay has an edge like you would expect but I think Smuggs' is second (or close to) in snow fall according some sources. Keep in mind that skiing deep powder can be far more tiring than on groomers for the youngster.
Steeps - Smuggs got more steeps, particularly on piste. The ungroomed, exposed drops over rocks or whatnot are beyond my level and look just as difficult and scary at both places; but I've been told by others in my family who skiied them that they aren't that hard
Park - I didn't see any at Jay. Maybe I didn't look hard enough.
Bumps - Smuggs has more. At Jay, I don't remember seeing much and they are kinda scattered.
Instruction - based on our one-time experience at Jay and many more at Smuggs, Smuggs wins in this catagories hands down. The only semi-private (for the family of 3) I ever paid for was at Jay and we got less out of that than out of any larger group lessons at Smuggs. The guy supposedly was a PSIA/CSIA Level 2. Didn't impress me.
Accommodation - there is no mixed review here. Smuggs is far better.
Food - Hotel Jay has very nice meals. Smuggs is kinda lame.
Nightlife - none at Jay outside of the hotel room so plan on skiing hard during the day if you're staying there. Smuggs is not a party town but it has plenty to do for a family with young children. There is some (tho not much) entertainment for adults also.
As for sampling, I would recommend doing no more than 2 resorts in this region particularly with a child who is an intermediate. These are pretty "big" mountains that call for at least 2 days to get a true taste and to explore. You're far better off letting your son rest between ski days so that you can get out there to adventure more. If your goal is merely to sample, then it really doesn't matter what ski areas you head to so long as they are new to you guys.
Good luck and have fun.