Toro owns Exmark, and has for some time, so you are largely choosing what color you like. For some additional 21-inch commercial-grade mowers you could look at the Honda HRC, the Ariens Pro or Classic, or one of the higher-end Snappers. It really depends on what you have in your area and which dealer you think you want to do business with long term.
Scag Tiger Cat 48-inch deck, Kawasaki motor
Lawnboy 10227 2T push mower
Stihl BG86 handheld blower
Stihl BR550 backpack blower
Stihl KM110R kombi system with lots of attachments
Stihl HS45 hedge trimmer 24-inch blades
Echo SRM210 trimmer