Well, there were several russian revolutions (3 to be precise). I'm assuming you're talking about last one, called October revolution - happened November 7, 1917 (October 25 on old Julian calendar).

Question is politically charged and it is still hard to get unbiased answer.

In the October revolution itself (defined as a moment of storming Winter Palace and following takeover of power) - definitely Lenin.

In the following Russian Civil War (western authors often bundle together revolution and following turmoil) - Trotsky had played critical role - being NarKomVoenMor, but so does Lenin and Trotsky was subordinate to Lenin. As NarKomVoenMor Trotsky was riding around in armed train, boosting Red Army morale by applying firing squads, assembling back crumbling frontlines by kicking asses of slowpokes - of course real military planning was done by a specialist Sergey Kamenev, a colonel of Imperial General Staff - Trotsky was merely applying Kamenev's design. Without Trotsky, Red Army won't take anything from Kamenev - who held off from becoming a bolshevik's party member until 1930.

Answer often depends whom do you ask - Trotskists tend to put Trotsky at least at the same level as Lenin, Stalinists will tell you that Trotsky was good-for-nothing and it was Lenin with Stalin who mattered most, Leninists will say that Lenin was far above anybody else.

Based on sources and books I've read - I'd say (hopefully, free of bias) that Trotsky role was lesser than Lenin. Lenin was chief strategist and participated in all vital planning, managing preparation and execution of revolution at high-level, while Trotsky role was very important and even critical, but not that encompassing.

Let me know if you want sources, I don't have them at hand right now - but be warned, most of them in Russian.