The only rule is they have to be an actual videogame character (no Ariana Grande jokes), and have to be from a series still alive in some form. So, Alis from the OG Phantasy Star would be disqualified as would Joana Dark since they're effectively dead.
If only going off recent years I would choose:
1. Chun Li - Arguably the face of the fighting game genre. Fun to play in Street Fighter 5.
2. Bayonetta - Star of two amazing actions games with a third coming soon. Took up the mantle from Devil May Cry while it was in slumber and ran with it.
3. Ciri - Amazing showing from the Witcher 3 and will be in a Netflix original series.
4. Sylvanas - Its 2018 and shes still a threat.
5. D.Va - Don't buy the Tracer hype. D.Va is B.Ae and the most popular character in Overwatch.
6. Zelda - Great in Breath of the Wild and will likely be fun to play in Smash Bros Ultimate.
7. Lara Croft - Crummy movie aside the new Tomb Raider trilogy has been pretty good.
8. Makoto Niijima - Down to throw fisticuffs while being an A student. Always stayed on my team in Persona 5.