If your only worry is that the fillers will get as annoying or never-ending as Naruto, then watch all of them. This is coming from someone who's seen every single episode of the great "Naruto Filler Saga" arc and forgotten 90% of them in the process.
Except for the Goat Island one, that one demands a skip.
I thought Ice Hunters arc was terrible.
Shitty filler kid.
Shitty filler pirate crew who's backstory we DON'T need to know
Strawhats get owned by… badguys who's schtick is ice sports? And let me remind you these jobbers give the crew a hard time after they dealt with CP-fucking-9!!
The best part of the whole arc is when Usopp and Sanji are fighting the figure skating duo. Sanji is useless against the female, but Usopp get's off a lucky shot with his Kabuto and nails her right in the face! Funny shit right there.
The last fight with Luffy and Don was alright as well, even though Luffy could've honestly owned the guy in a couple minutes.
And honestly, I thought Lil' was a pretty acceptable filler kid. Jiro and Phoenix can go ahead and fall off a cliff though.