Keep in mind that you've got the pentode-triode switch on Bob's amps, and that you can adjust the bias for your output tubes. That will flavour the sound almost as much as your tube selection. Jim McShane swears by the Gold Lion KT-88s. He also sells the Russian New Sensor Tungsol KT-120s, which as MontanaWay says are quite robust, deliver great sound and are probably the best bang for the buck.
I have a rack of KT-120s and KT-88s acquired from Dr. McShane, who is my go-to guy for Russian tubes; he really torture-tests before shipping them.
I'm kinda partial to my New Jersey TS 6550s. Those 50-year-olds just look so pretty and they've got a certain sumpin' about them. Problem is you've got to sell your first-born to get eight of them NOS nowadays. They're several hundred bucks apiece.
Starting out, I would take Montana's advice and go with the New Sensor TS KT-120s. Get them from Jim at www.mcshanedesign.net
and you won't be sorry.
I would also scout about for some NOS General Electric 12BH7As for your driver-board slots, especially in the front holes. They're not expensive and are very sweet, and also will very much affect the quality of your sound.
Hope that wasn't TMI. Welcome to tube-land, a/k/a Tommy's Holiday Camp.