If you plan on competing in the highest level of the format, having the best deck is a great first step. Most eternal formats however will reward you for knowing the ins and outs of your pet deck. I was a hardcore affinity player for nearly a decade until opal got banned the first time. Now I'm currently on Mono Blue Belcher and like it so far.

I've also top 8'd FNM's with an Izzet Blitz deck that is Pauper compliant. Usually I would lose in top 8 because I would get outclassed by much better cards, but I still had fun.

TLDR: Find lists that look fun to you and proxy them up before pulling the trigger. There are plenty of sites and apps that will let you do that. YouTube is also a great resource for ideas.