I am tempted to vote for Intamin just because of Tornado at Bakken. The way that spinner tried to kill me should not be legal. Well, it should be, and mandatory if you want to be considered a proper enthusiast. Love that coaster to bits. Realistically, a manufacturer with so few instances of spinning coasters shouldn't be crowned king.
So, I am going with Maurer Söhne, mainly because even though some of their models are meh (eg: Tarantula or their SC2000 models), when they get them just right they are an absolute blast and amazing (eg: Dragon's Fury, Winja's). I think they have shown they are capable of many things, are quite reliable and are generally good across all examples of that model.
As for Mack, I tried Le Twist at Le Pal and although it was good, it felt almost too controlled for a spinning coaster. I'd like to give a spin (pun intended) to their new X-treme spinning model before I decided if Maurer still reigns supreme.
Zamperla, Reverchon and Gerstlauer. Second tier spinners. Maybe Gerstlauer is a bit better and gets extra points for having the balls to install the first spinning coaster with an inversion, but generally very meh.