My suggestion is to get him a gift card in the amount required to purchase the helmet and Bluetooth device or one with it already installed. Helmets are screwy in the way they fit. A size large in one brand might be a size medium in another. Then there are the shapes to consider. Some are almost perfectly round and some are very oblong. My point here is don't just buy one. Let him pick and choose to get that perfect fit. And is not an easy process. But to you direct question as to which is best, it's really a toss up. I've gone both ways with my CB set up and Bluetooth is similar. The thing with Bluetooth though is the unit can be easily removed if bought separately should there be problems or updated devices. There really is no, one way is better though. JMHO
I agree with Hogcowboy. To many variables to make the decision on your own. I might not even buy a gift-card, just print up a "coupon" indicating he can pick the helmet and communication system of his choice. They may not come from the same place.
I have a Bilt Techno bluetooth helmet and have been happy with it. It's my first bluetooth helmet. Only really rode in the dirt and a couple of weeks on the street until the early 90s. There was a long break and then a couple of years ago got a cruiser and have been on the streets since.
My son got a helmet and we bought a separate bluetooth to put in it. Personally I think that is the better way to go.
I'd definitely go with a separate unit, that way if he gets another helmet, it can be transferred from helmet to helmet. They're usually a better quality than some of the built in units too. I have six helmets for three different types of bikes, so its nice to be able to switch up either of the two Sena bluetooth units that I have with whichever helmet I go with.
I agree with the separate unit, mine has outlasted 2 helmets and might just outlast the 3rd. You can also pretty cheaply buy the permanently installed speakers and attachment part and move the expensive portion from helmet to helmet in seconds if he uses more than one helmet.
I'm partial to SENA brand, there are others but they seem to be high quality and fairly trouble free.