Advice on travel from Avignon to Antibes

Avignon to Antibes is about 2 1/2 hours by car; by train, I think you'd have to go via Marseilles.
'Scenic' is in the eye of the beholder. No matter how tired out, it would be crazy not to stop along the way in at least Aix.

A direct TGV from Avignon TGV station (outside of town) to Antibes takes 3 hours. (It travels via Marseille, but you need not get off there on most departures.) There are also direct trains from Avignon TGV station to Aix-en-Provence TGV station, also outside of town; both have easy local shuttles; no bag storage. TGVs are cheaper when reserved ahead (e.g., now).

You might not need a car around Antibes, since there are frequent trains and buses along the coast. The 2.5-hour driving route is all on a major highway, so you probably wouldn't be tempted to stop, although a stop in Aix would be right on the way. Scenery from the train should be similar to this drive.

So I wouldn't necessarily choose the car based on speed. You might choose driving if you wanted to follow a slower route, either inland via more Luberon villages and the Gorge du Verdon, or poking along the coast.

I agree with Laura. If you want to right to Antibes without stopping, take the train. If you're going to be stopping off, particularly in places not right on the coast (and so not on the train line), rent a car.