I have read a few. Don't really care for romance in a series so don't know that many romance ones. I did read around a hundred chapters of ruler of the land and don't remember where I left off but I enjoyed reading it. Will probably continue it soon and also start reading the breaker.
1. The Gamer, Noblesse, Tower of God, The Legendary Moonlight Sculptor, Black Haze, Red Storm, RPG, World of Law and Order and other few that I can't recall.
2. I liked most of them and am not one to choose favorites. But the first three I mentioned are quite popular so you should read a few chapters and decide.
The Gamer - The main character gains the ability called the gamer. He finds a new world hiding right around him called the abyss and his ability is unique even among the the people in abyss as he is able to comprehend the world as RPG type game.
Tower of God - The series is great not because of the main character but the world, setting and overall story and potential. The story takes place in a tower which basically is quite large and the outside world is rarely discussed. But the tower is huge and hosts many unique environments. Each floor is said to be big as a continent and the goal of everyone seems to be the top of the tower. We don't know how many floors are in the tower. No one knows what awaits but there seems to be a promise of fulfilling any wish or desire. I recommend to anyone liking fantasy, mystery action and adventure.
Legendary Moonlight Sculptor - It started only this year so it has 42 chapters. Its about a dark gamer playing a VMMORPG. I have read the light novel up to volume 25. The light novel is ongoing and it is being translated but its much ahead of the webtoon so no worries there. The main character has been poor most of his life so is quite greedy. It is quite funny and enjoyable so try a couple of chapters. It doesn't really deviate from the source except a few minor details. I highly recommend it.
Red storm - Action, adventure, fantasy. Has a desert setting and has tribes struggling for power there. Good action series based on a novel, ongoing and has 172 chapters. The young glow(Glow~chieftain) meets a mysterious man who is super strong and the kid takes the man back to his tribe. The man later becomes a teacher to the young glow and teaches him from his knowledge of otherworldly martial arts. Strength and skill is quite necessary to survive in the harsh desert filled with powerful and unique monsters. Recommended for those who like action and fantasy.
RPG - Highly recommend. Randomly stumbled upon it. Awesome series. Its quite funny and has many likeable and lovable characters. The design and looks may be a turn off but I highly recommend it.(How highly you ask? So much that I had to type highly recommended twice). But kidding aside It currently has only 37 chapters but the series is quite fun. I would suggest anyone to start reading it if you are planning on reading anything. I seemed to have over hyped it but it is a lighthearted ,funny and enjoyable series I must say. Also from its name you could have guessed it takes place in a game world as in VMMORPG. The comedy, characters make the series just lovely. So if looking for a comedy series I would definitely suggest you to try it out.
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3. I have a long list of things I have to read but I will probably finish ruler of the land and breaker and new waves before other longer ones. I like action adventure and fantasy ones so most series fall in that genre. To name a few that I plan to read- Ares, Blind Faith Descent, City of the Dead Sorcerer, Distant sky,Dark Air, A fairy tail for the demon lord.
4. Don't mind romance in series but I can't say I'm particularly fond of it. I do like action series but it is not a must.
5. Recommend RPG, Tower of god , Legendary moonlight sculptor(also recommend the light novel), Red storm. Also try black haze.