I started with a pack of cotton gods that I bought as part of my "introduction to vaping" set (yeah, skipped the whole pods/stock coils step) and always noticed a little twang initially which I assumed to be break-in, and a friend gave me a strip of bacon and something else I can't remember that looked similar and I really couldn't tell much difference. Also tried the laces and stuff that came with a couple of tanks - same again...
The big thing was putting unflavoured juice in - that really highlighted just how "cottony" they all tasted at first. Noticed (less of) a difference with flavoured juice too.
Had a chat with the guy in my local b+m and he gave me the sample pack of coil master muji - waaay better. Almost no mistaste right from the off.
As for the upcoming muji/labo comparison, I'll try to be as consistent as possible. I have 2 galaxies rdtas and 2 Picos, so I'll fresh build both, one with each, as close as I can - the best "side by side" scenario I can think of.