Like ThePolakVet confirmed before : 'Russian' organized crime is divided in criminal gangs of a lot of different ethnicities. All of these gangs are very powerful.
Gangs like the Solntsevskaya ( mostly ethnic Russians and some Russian Jews) however are in a league of their own. They are capable of doing the drug trafficking and extortion most OC groups do, but they also carry out sophisticated schemes.
Right now Ex-Soviet OC is much more powerful than the American Mafia. But I wouldn't say they are more powerful than the Italy-based organizations like the Sicilian Mafia or the Ndrangheta. These two gangs also have a large and powerful international presence.
Worldwide I think Ex-Soviet OC, Italian OC and Triads are the most prevalent.