the flashforge filament that came with my original printer - was pretty poor, was nearly 3 years ago now though.
Since then I've used dozens of different makes and types. My all time favourite filament is reprapper tech ltd pla. Phenomenal stuff and decently priced.
I'd also recommend all the polymaker filaments - with a particular emphasis on polyflex. Just the best flexible filament around.

I've also used a bunch of dirt cheap pla from amazon and ebay. For the money, it's all been okay. I honestly don't think you get crap filament anymore.
I've never had any issues with thickness, moisture, clogging etc.
The main difference between good pla and cheap pla is the cheap stuff will have a very slight shrinkage and the good stuff won't.