I enjoy novels which have the protagonist with a system as well. Here are some that I enjoyed, though they may have been listed already: Black Tech Internet Cafe System Gourmet in Another World Ultimate Scheming System The Almighty Coach The Mech Touch Neet Receives a Dating Sim System Fishing the Myriad Heavens World Domination System There is also, The Library of Heaven is Path, which is not exactly a system but it does share some elements.
Monster Paradise guy has a summoning system. The system has a lottery wheel and upgrade cards and such.