I have used McCloskey's Man-O-War and found it entirely suitable, perhaps the easiest to get a good brush finish. Readily available and a bit cheaper, and always does well in the tests I've read.  But don't let price make your decision, buying good varnish isn't really the place to worry over a few dollars, so don't get cheap, poorly rated stuff.  Petit Z Spar Flagship is rated top of the line and costs more, and maybe rates with better U/V protection.  These two are amber hued, which I like (others don't like - that's a personal preference).  Petit Z Spar Captain's is supposed to be less amber hued, I think, although it is still listed as amber colored, and maybe the best U/V.  You can spend hours reading up on varnish and real-world durability tests on the web, but can't go wrong with any of these, or the Interlux Schooner.  BTW, I like the piney smell of the Interlux best, for whatever that is worth.

Hi Sundance, 

are you in a place where CLC can't ship (e.g., outside the USA)?

with covid, i have been just having stuff shipped so finding quart sizes has not been a problem.  i have not looked recently so am just curious that you can't find any?

fwiw i have also used zspar/petit captains varnish and epiphanes and they all worked just fine

h