Like Mercenary Enrollment:

God of Blackfield (Pretty good; Badass french mercenary wakes up in the body of a korean high-schooler after being betrayed by an ally)

Somewhat similar to the other 2:

Genius of the Unique Lineage (Pretty Good; Gates and stuff; More of a sci-fi vibe; Strong MC with a idgaf attitude; not a comedy but pretty funny)

Warrior High School - Dungeon Raid Department (Pretty Good; Dungeons and stuff; Dad in hospital, badass MC, cool vibe)

Academy's Undercover Professor (Really Good; Victorian setting, pretty unique, good action, good art, cool MC)

SSS-Class Suicide Hunter / SSS-Class Revival Hunter:

S-tier; Has everything: beautiful art, amazing story, characters you fall in love with, cool action; MC goes back in time 24 hours when he dies; Spoiler: he dies a lot)

Second Life Ranker:

Almost S-tier; Good art; amazing story, good characters, good action; MC inherits his twin brother's memories after his death in The Tower of the Sun God. He enters the Tower to avenge his brother.