Depends what you want to study. "Russianists" in poli sci are spread out. But there are probably a number of others whose main focus on substantive issues (e.g. IPE, federalization, etc) apply to the region and thus use Russia/FSU as a case study, though are not Russia scholars per se.
Places to study Russian/FSU politics are places that generally have strong area studies departments, for instance: https://www.carnegie.org/news/articles/russia-area-studies/ and http://iseees.berkeley.edu/sites/default/files/u4/FINAL-ASEEES-assessment-report.pdf.
George Washington's political science department is also good in terms faculty who work on the region.
This list is by no means comprehensive, but it should give you a good idea of some scholars working on Russia and the former Soviet Union: http://www.ponarseurasia.org/members