In both RET and FET, raindrops form spheres (well, roughly) because of surface tension - it has nothing to do with gravity.   In RET, the gravity exerted by a raindrop is vastly too weak to have any effect on anything.   Surface tension is a force that's stronger than gravity over very small objects - but vastly weaker over large objects.

Raindrops are spherical when they move slowly - but when they pick up speed in air - they are gradually distorted into other shapes by aerodynamic drag.

So this argument has no bearing on whether FET or RET are true - the answer is exactly the same.

The answer is also the same whether there is true gravity (per Isaac Newton) on an infinitely large flat earth - or whether there is universal acceleration (per the Wiki).

Just to make his point perfectly clear. Hydrogen bonding will, in fact, make a semi-sphere of water even when it is resting on a nonporous substance. AKA HPL laminate on most counter tops. That sphere shape of water is caused by the surface tension which is the result of all those hydrogen bonds present in water.