I am a HUGE HxH fan. But it has some HUGE lulls and pacing issues. Also animation wise it's ups and down. Some scenes are up there, but some are really bad.
I'd say this: it's too early to put frieren has the best anime ever. Does it have potential for it? Absofuckinglutely. The 28 episodes we just got were absolutely flawless, pacing was incredible, story telling was S tier, the world is amazing etc.
But what if Season 2 sucks? It's too early to tell.
If it stays the course with quality, it will no doubt be the best anime that ever aired for a while. The fact it does everything right while completely avoiding the usual japanese tropes (you know what i'm talking about. Incel shit, sister loving, weird Japanese fucking nonsense) AND while having a power system that makes sense (like Nen in HxH) is truly a testament of how good it is.