Beyond any doubt Shani Dev is the boss in the kaliyug, but you can't underestimate Rahu's powers. Rahu is considered to be the most powerful planet among other planets, because it has the sole power to extract good benefits of other planets.
Rahu is the only planet which can cause solar as well as lunar eclipse. It can grab the energy of any planet and responsible for causing Kaalsarpa Dosh and Pitar Dosh. Rahu is a shady planet that does bestow failures, struggles and frustration in one's life. However, if Rahu is in proper planetary position it can make a beggar to king.
Depending upon kundali to kundali, Rahu may be stronger in degrees and a person who is going through Rahu Mahadasha would face more consequences than Saturn (Shani) but planet to planet nobody is more powerful than Lord Shani.