Here's a few thoughts from a guy who tries not to over think everything; I only ever used amber lens when shooting sporting clays or skeet on dreary days. They give great definition in poor lighting conditions but I would not want them for general use. If you choose gray your will adapt to them rain or shine, spotting fish is a matter of acquired talent and I personally don't need different colors for different days. Remember that is a personal thing and you or others may not agree with my approach to lens color. Last but not least, regardless of which glasses you buy, whether they are a cheap 'Fish Finder' or made by Zeiss you must keep and protect them. I've been relying on the same fishing glasses for 20 years and haven't scratched them yet or lost them. Once you become used to the darkened / polarized view of everything and your glasses are helping you to locate more fish they will become as valuable as the rod you are carrying and you'll protect them just as well. I guess that was meant to say; whether they are bargain basement or top of the line the biggest danger is losing or breaking them.
Once you get used to wearing them all the time you'll love whatever you get.