I have been very happy with Interlux Schooner
varnish. It seems to hold up very well and applies easily. As noted above, Epifanes has a good rep too.
As a general observation, I would avoid the 2-part applications. I have tried one of them with disappointing results. If you goof the ratios, or something else goes wrong during the application, they are tough and hard to remove once they've set.
Also, be careful that the
varnish is not only marine grade, but also that it is rated for exterior use. There are "marine" varnishes that lack UV inhibitors, which are suited for interior use only. The exterior marine varnish will state specifically on the label that it contains UV inhibitors.
P.S. Welcome to Sailnet! Check in here before your next project -- there's a lot of knowledge base and it's likely someone would have saved you from this headache had you ducked in before the varnishing project.