Honestly, I don't think I ever tried IKV RY4, but I tried a few. And I make my own.
I DO recommend trying - to start, it can be VERY simple:
Nic from Nude Nicotine.
VG & PG from Essential Depot.
& RY4 Double flavoring from The Flavor Apprentice.
Mix it at say 15% flavor and whatever VG/PG ration you want.
Then adjust and experiment.
I add some "AP" for a hint of nutty. And I add some Bavarian Cream for creamy (the diacetyl-free version).
And I've lowered the flavoring and nic slowly over time.
I vape it all day every day, and can't stand any store-bought juice anymore.