Tough to say. Right now, I think I'd take Malkin. Its easy for me to say that because he has a Cup and a Conn Smythe on his resume, while Ovechkin has ugotz in terms of playoff success- personal or team- on his and is one of the worst defensive players in the league. But their careers aren't over either and Ovechkin should reach 1,000 points within the next 3-4 years or so. Its an interesting debate.
Alex Ovechkin's playoff career numbers: 58 games, 31 goals, 30 assists, 61 points, +9, 275 shots. This is personal success. He's 3rd in goals per game among players with a minimum of 20 playoff games (since 1996). If his team hadn't let him down, he'd have been to a Stanley Cup Final at least by now.
I mean, I think the choice is close, but people give Ovechkin grief for his playoff performances, when to me that just makes no sense at all.