From my definitions of the terms, VNs are non-ero. Branching from VNs are eroge, and branching from eroge are nukige. You get things like Nakige and Utsuge, but they are more plot-related categories than the others.
It doen’t think it really matters if there are very few VNs compared to eroge, there is still a difference. But we can compare Kotarou to eroge protags too if you want. I’ll just list from my VNDB list until I get to one who doesn’t hold up to Kotarou.
G-Senjou
Tomoyo After
Kara no Shoujo
Narcissu
ONE
Tokoyo no Hoshizora
Utawarerumono
And then my love for trashy romance stories gets in the way.
Still, there are lots and lots of VNs that out-do Kotarou. There are lots that are worse, but lots that are better. If you think about it, Kotarou is an incredibly character-less character. He is malleable, and everything he believes and holds dear is defined by the choices you make. He doesn’t have a defined personality outside of the common route, because he becomes so different throughout rewrite.
The Okabe Rintaro we know is a person who doesn’t care about the real world, but not in the way you might think. All he cares about is the people inside his world. Basically, he dedicates himself to the people around him, and doesn’t know what to do when they aren’t there. He believes that everything should have an answer, and that if it doesn’t appear to have one you should search for it. He’s kind of arrogant, and won’t let something go, even if it would be more beneficial to just be a bit lax.
Of course, the tricky thing with choosing Okabe is that he’s from a time travel story. His personality is different over different world lines, and it can be very drastic. Just look at the Gamma and Omega AF. Completely different person.