Cradle series by Will Wight What's there to say? I fall for the simple stuff. Even if something goes amazing using a twisty premise ( the Ancient Demon Sect arc in ISSTH with Meng Hao having a father and brother from another time was actually superior to his real parents showing up, or the amazing tangle of circumstances the author of Regressor Instruction Manual manages to weave together in every arc) I still prefer this kind of thing. Just a guy who wants power and admits it (there is the whole his home might be dsetroyed if he remains weak, but he does admit later what he really wants is recognition strength will give him. And that's okay.)
Both love to tinker ( Rudy's various projects like the magic armor, and Lindon's desired profession is working with Remnants as a Soulsmith which requires quite a bit of training and work), both have questionable points disqualifying them from perfectly heroic status ( Rudeus is a major pervert even after his many moments of growth, has a lot of regrets even in the new life such as those caused by the mass teleport incident. Lindon is greedy, realizes due to Underlord breakthrough he practices so he isn't looked down upon like he was most of his life and while cunning, he tends to go for big risks whenever there is something in it for him. It tells a lot the typically reckless Yerin is the one pulling him back sometimes.) and both willing to go around for their goals even if wandering itself has little appeal to them. Oh, and their starts are about being unsatisfied with their starting point. Rudeus latched onto magic and endured daily massive headaches as a baby to increase his magic power and we see the original timeline in first book Lindon wouldn't let his "Unsouled" status stop him from cultivating to at least Iron body in old age with no help aside from what can be gained in his tiny, primitive hometown. That's a decent level for his hometown since those guys only know about next two stages ( Jade spirit, and (low)gold). Yeah, he reminds me of Rudeus too. Not in sexual tendencies though, completely different there.
Trash of the Counts Family was already said... so ‘My Husband is Suffering from a Terminal Illness’ it is!
Empress's Gigolo. This novel isn't about a particular genre, it has a bit of everything. This is a FUN novel. Imagine someone getting advance weapons like GUNS, GRENADES, BIOLOGICAL WEAPONS, POISON and he can shuttle back and forth between Earth and a fantasy cultivation world. In the era where there were lots of kingdoms, brave warriors with strong physical attributes, fights with swords, bows and arrows. Imagine a weak human like him getting wild there with guns and grenades, killing strong and powerful people left and right, going back to earth after cultivating, killing influential, powerful people left and right, going back and bringing more weapons and modern items, developing the other world for the empress, That's the MC. There's also things like cultivation technology, science meets magic, other races etc. What happens when someone from a feudal era sees the modern world etc. What happens when modern world meets godly cultivators etc. There's also interplanetary travel. Otherworld and modern world world building. MC builds influence in both worlds etc. If I would have to describe it in one word it would be: Satisfying You'll never feel like it lacks anything unless you're a big justice nut. The MC gets married, builds a family and has a child, sees his child get old, sees his Earth Family get old (because 10 days pass every 3 days in the other world), becomes respected, progresses a medieval civilization all the way into pre-information age, scares cultivators with nukes, scares 1st world countries with godly cultivators. It's just f-ucking-tastic
The last post triggered me to recommend a same deal turned upside down. Ye olde cultivator vs modern hero society, very inventively named Cultivator vs Hero Society. I don't know how good or bad is it, never read it, just heard of it, read the plot summary and moved on because I had plenty of reading material to entertain me.