The Dutchman is likely to start against Los Blancos in the first leg of the Champions League round-of-16 clash at the Bernabeu on Wednesday.
"Van Persie is on very, very good form," The Guardian quotes Ramos as saying. "We hadn't seen him this good for years. He's quick, strikes the ball well, he's a constant nuisance.
"[Wayne] Rooney's different. He's hard-work, heavy going. He enjoys the physical challenge. I prefer that, to be honest. I like that defender versus striker battle, that challenge."