On the car would be best, the whole rotating mass is balanced. Disadvantage-finding a place that can do it, the cost, and the wheels have to be kept on the same corner, marked when removed and put back on exactly the same to stay balanced.
A good spin balancer can do an excellent job, but the shop may not have the right adapters or a tech that feels like spending the time to figure out what will work to get the wheel secured on the machine. Our old balancer didn't have the right hubs, the new one(2yrs old) can be set up on wires. Another nice thing, you can rotate and remove your wheels and not worry about balance.
Bubble balancer? I think I know a guy who still has one burried in the back of his storage area. On a more serious note, When he digs that thing out, he can do just as good a job as any spin balancer. And depending on what hubs the locals have on the spin balancers, you might need to go the low tech route.