If it were a wheel bearing going bad, you would hear it long before you would feel it. Bad wheel bearings have a very specific noise they make, and you usually can't even feel it. If it's a wheel bearing and you can feel it, you're about to lose a wheel.

My vote is for a bad tire or an out-of-balance tire, with a side bet on some kind of front-end joint or connector problem. Also possible that you drove over a rock or a curb and dented a wheel rim.

Outside chance that it's a warped brake disc combined with a sticky brake caliper (latter can cause the former), but I'd think that you'd notice it more significantly at a much lower speed and that you'd notice it more specifically while braking rather than accelerating.