Flex queue vs Solo Queue which do you pick up

This summer when DQ had 5s no one was able to get a full 5s team going. i know there was tryouts and having a full team was not manageable to do. there can be issues with having the right champions with lack IP or masteries. if a jungler misses a pick when needed to that pick, it will be hard to run through the rest of the game.

Flex pick and team 5s in the same bracket is a good separation but i assume 80% of the players will go to solo once the teams start assembling their teams.