I've found a few novels with really good translations in my time here (Antimagic Academy and Reincarnate as a Sword to name a few), but I think that at least 90% of the novels I try to read end up having pretty glaring grammatical errors (terrible grammar, words that should be part of a sentence not being written into it for no reason making the sentence a guessing game of what it's meant to be saying, etc) that would be fixed by someone with a half-decent grasp of English having a quick read through. The odd mistake here and there is fine as the original authors don't get paid for a lot of the novels on this site and the translators usually don't (and if they do it's not a lot) either. What I'm talking about are series where there are multiple blatant issues per chapter that works to take you out of the world on a consistent basis. Short rant aside, could you please recommend a series or two that has pretty solid translation quality? I lean towards action or one with some action elements in it but that's not 100% necessary, especially if the recommended series has a really solid translation and is genuinely good.
I wouldn't even say you can just go to certain sites, because it varies from translator to translator (and editors as well I guess), and not even just recommending a novel is certain either because it's not uncommon for a novel to switch hands between people (and that usually ends up with a worse translation). Deathblade & Ren immediately come to mind, but then the options for novels are pretty limited... (ISSTH, Coiling Dragon, Desolate Era, etc.) I'd say The Amber Sword has a pretty solid translation, but more importantly the editing to get rid of a lot of the redundant word padding makes it for a much smoother read. Plus the genre is a bit different from your usual cultivation novels. (Translation speed is pretty slow though, but there's a big stockpile of chapters to read at least.) For some korean novels there's The Second Coming of Gluttony, The Novel's Extra, and Reincarnator. Their translations are all solid. As for Japanese novels... To be honest I don't know of any. One of my old favorites is Mushoku Tensei but half of the translation was poorly edited MTL. Like most JP novels (from my experience). Or I guess actually I've read Lazy Dungeon Master which has a pretty good translation iirc. Well I don't read a lot of JP novels so maybe someone else can fill in the blanks.
Fallen Monarch. Has a lot of work put into it when it comes to TL quality, as well as being edited for readability and grammatical issues.
Unfortunately a good translation doesn't mean the novel is any good. Wuxiaworld stands out in that regard since their translators and editors are really good but the novels they pick are often generic (The entire Er Gen line, kek), or straight up awful (ATG, AST, SOTR, MGA, DP, or virtually all of their novels with like 4-5 exceptions). And even those are often not that great. Overgeared and Praise the Orc are supposedly fairly good, as is City of Sin (even if the author, 100 chaps away from the end, lost his mind (again)). Monarch of Evernight is alright (better than generic but not good either). I'd recommend Return of the Swallow (etvos passion project, kinda) or Dungeon Defense.
It depends on the translator. Big website like volare and wuxiaworld have some standard for their translators. Qidian on the other hand is where you can find a godlike translator and an absolute garbage translator with kindergarten level grammar translating the same novel. Because they changed translator occasionally. I'm still bitter till this day because such a good novel like Martial Art Master get a horrible translation.
The Ultimate Evolution is pretty good (except for the horrible first 7 chapter prologue, which I would recommend skipping) both the novel and the translation.
Yoraikun Probably one of the best Japanese-English translators. Has translated several stories, most of them highly enjoyable.