Fountain Pens

I am about to buy a Platinum Plaisir, Lamy Al-Star, or a TWISBI Eco (or possibly all of them) but I can't decide which nibs. Even physical shops around here don't have inked pens to try. Problem is different makers and countries describe nibs differently, eg with Japanese F often being like European EF apparently.

Any tips? I hate scratchiness and like some stroke variation, but I generally prefer finer nibs usually on cheap paper. If that means anything, my Muji pen is about right but a liitle too scratchy. My old Pilot F is excellent.