You don't mention what your son will primarily be using the binos for, other than sometimes coming with you. Will it be stalking, birdwatching, sports games, horse racing, something else, or just general use? There may be no point in buying him full-size binos if he would prefer a small pair that he can stick in a jacket pocket.
If it's full-size binos, here's my take on the Swaro CL 8x30's, the EL 8.5x42's and the SLC 15x56's. Keep in mind that I am the wrong side of 60, so my eyes will have deteriorated compared to those of an 18-year-old!
The view through all three sets is superb, but the pair that gets most use by far is the 8x30's. They lose little in terms of light gathering at first/last light, and are just a delight to carry and use. If I had to live with just one pair of binos, it would be these, hands down.
The 8.5x42's were the first pair I bought, and they served me well for years as my main pair of stalking binoculars. These days they get least use, as when stalking now I use binos in combination with a thermal spotter. I find the 8x30's make the ideal combination for this, as the extra weight of the spotter gets cancelled by the lighter weight of the binos. I wear both on the regular neck straps, not bothering with a bind harness or similar.
The 15x56's are much more of a specialist set of binoculars, and were bought for static birdwatching and stargazing, but they have ended up getting used a lot more than I anticipated on dog walks, etc. Sure, they are significantly heavier than the other pairs, but still easy enough to use handheld without a tripod, and I wouldn't hesitate to take them if I was going to be out for 2 or 3 hours at a time. I don't take them stalking, as the 15x magnification isn't required for the type of Southern woodland stalking I do, but they give an uncompromising view of any wildlife if just general nature-watching.
Whatever you buy, I am sure your son will be delighted, and will have a pair of quality binos he can hopefully treasure and use for a lifetime.
