What a weird request, but OK, I'll humour you.
Favourite (real-time/action) combat systems: Soulsborne games and Nioh, followed by Dragon's Dogma, Monster Hunter, and Ys: Oath in Felghana/Origin.
Favourite character designs: uh, my characters in Fashion Souls
or my avatar (not playable though). But for a pre-set playable character, hmm, I like Alucard (Castlevania: SotN), Kain and Raziel (LoK Soul Reaver), Gabriel Belmont (Castlevania LoS), Athena (Borderlands: TPS), Shadow (FF6), Agrias (FFTactics), Chris Lightfellow (Suikoden 3), Orta (Panzer Dragoon)... to name a few with various art styles.
Favourite OSTs: my all-time favourite is Castlevania: SotN, probably followed by FFTactics, the Panzer Dragoon series, Bloodborne, Suikoden series, Wild ARMs series, Xenogears, Guilty Gear XX, FF6, Castlevania: Bloodlines... well I could go on.