Seems to depend on whom one wants to believe. I've never used vinyl ester resins.
If you read the literature from the epoxy people most seem to say that their resin is definitely superior (as far as imperviousness to water) to polyester and leave vinylester kinda to the side.
If you read the literature from the vinylester people, they say that their resin is better than epoxy in resistance to permeability to water.
I've used isophthalic and orthophthalic polyester resins from cheap hardware
store brands to high end surfboard quality and there is a wide variety in water absorption characteristics among them.
I've also used West, System Three, Mas, Resin Research
and a variety of off brand epoxies, and I can assure you West and System Three are definitely not impermeable to water. I've only used Mas on dance floors and table tops, so can't tell you about it, and the story is still out on Resin Research
because I've not yet done any work on previously coated surfaces to find out. Off brand epoxies don't get used in critical applications.
Within any 'class' of resins there are different formulations, any of which will affect the properties of the specific resin.
From the OPs' perspective, coating dry wood or repairs
with either high quality epoxy or vinylester resin, followed by a specific purpose two part epoxy barrier coat is the probably the best (simplest and most economical) route
. I'd certainly not trust either epoxy or vinylester alone without a specific barrier coat before bottom paint