Probably my favorite VNs come from Love Conquers All Games (Christina Love's stuff). The best is probably the Hate series: "Analogue: A Hate Story" and its direct sequel "Hate+", but all her stuff is good. You play a space investigator trying to figure out what happened to a derelict generation colony ship by reading log files and conversing with the still-active onboard AI. It's way better than it sounds.
Another top favorite is "World End Economica". Designed by Isuna Hasekura, better known for "Spice and Wolf", it is a rare example of finance fiction in the VN space (which takes place on the Moon and features Hasekura's wonderful blend of fantasy, finance, and romance).
I second the Steins;Gate series. Taken together, S;G and S;G0 probably tell one of the best stories ever told... though it requires a great deal of time and thought to figure out what's really going on behind the scenes. All of Mages stuff is kind of like that, though I think Steins;Gate is the only one where it's actually worth the effort.
Finally, if you're just looking for some happy goofy adorkable romance, Pixelfaxe's VNs are all good. You may as well start with their first VN, "Ace Academy", which features a bunch of college aged kids at a giant robot fighting academy, but there's also their fantasy isekai "Crystalline", their reverse isekai "Ethereal Enigma", and their upcoming space adventure "Astral Ascension". The art is beautiful, the girls are gorgeous, and the voice acting is the early work of some people who ended up kind of famous (Amalee, Sydsnap, and others). Really fun stuff.
To anyone who isn’t interested in Japanese-style visual novels, I’d recommend Scarlet Hollow. It’s an “immersive horror-mystery” illustrated by Abby Howard (of The Last Halloween fame). It’s an episodic title (the first episode is free on Steam) and it is not finished yet.
VA-11 Hall-A! One of my favourite VN if my instance url didn't give it away. It's not too long, listen to the start telling you to get cozy and then mix drinks and change lives.
@Ingrid_Skovgard If you like Ace Attorney, then the recently released love letter to the series called "Attorney of the Arcane" is a great, great next target. The characters are captivating and the gameplay offers a few good twists on the standard formula. It gets pretty hard at the end, but not in a way that you can't solve by just paying close attention to the case. It's gotten several updates since its launch fixing typos and bugs, so the experience should be top-notch now. If you do try it, do tell how it goes.
Loved the anime of steins gate. Think I've got the elite version of the VN but thinking maybe i should of got the OG. The frozen anime frames look a tad weird to me
I also really enjoyed One Thousand Lies, because it has a thought-provoking coming-of-age story and completion unlocks a very clear explanation and analysis of the story which contains some cool things you might have missed along the way: https://keinart.itch.io/one-thousand-lies
Zero Escape series: I love them, even ZTD. Some hated that ending, while I don't think it's that bad.
Infinity series:
Never7 is very slow, and romance heavy with bit sci-fi. I don't like this game
Ever17 starts getting better, leaning more towards sci-fi, but can still be quite slow
Remember11 is the best among the infinity series, it's sci-fi horror mystery. Some say the ending is kinda incomplete due to budget issue, I'd say that the ending is bit of cliffhanger, but the main story is more or less complete
Raging Loop: a really good supernatural horror mystery. Maybe even better than Zero Escape series. I highly recommend this.
Paranormasight: a solid horror mystery VN released this year, there's some smart puzzle and writing, but the ending is kinda unfulfilling.
Meitantei Conan & Kindaichi Shounen no Jikenbou: it's fan translated DS game. I am a Kindaichi fan, and the Kindaichi section is good mystery. The Conan part is ... well, I'm not into Case Closed, their mystery always feel bit geared towards kids.
Danganronpa series: There are parts of the games that I like, but somehow I couldn't stand the annoying character tropes prevalent in the series, and also those fan-service-y part. Some people dislike the final ending, I'm ok with it.
Root Letter & Root Film: Root Letter starts out good, but somehow one of the endings ruined the whole game. Root Film starts off promising, but the deduction part is kinda stupid and boring. Also the ending is not good.
Policenauts & Snatcher: They are quite interesting. I enjoyed Policenauts quite a bit. Snatcher is good too.
Silver Case: couldn't stand the banter and writing. Everything feels so slow, and very Suda51.
13 Sentinels Aegis Rim: quite a solid sci-fi kitchen sink visual novel. It does feel like they are biting more than they could chew though.
AI the Somnium File: okay sci-fi mystery VN, I don't think it hits the high of Zero Escape.
Fatamorgana: I thought it was a murder mystery VN, didn't realize it's more romance, couldn't get into it.
Steins; Gate: I tried to like this game so many times. Okabe the main character is very grating.
I've probably missed some, I recently bought Root Double, which is from the co-writer of the Infinity series, heard that it's really good.