My advice...stay with a speaker that is pretty transparent like the 70/80. Some speakers will color the tones of the models so much that they will no longer sound like the amp that is being modeled.
Jensen used to make a MOD speaker for modelers, but I'm not sure they still do. Celestion had the G12 Century Neos, but they were pretty expensive and have also been discontinued.
I saw a post on another forum where a guy ran his Vox through a cab loaded with Greenbacks and commented on how "horrible" the amp sounded....the Greenbacks aren't a good choice for a modeler at all.
Guitars: 2003 and 2004 American series strats, Squier Classic Vibe 50's Strat, Squier Deluxe Strat.
Amps: Line 6 Spider IV 120, Vox AD50VT 212, and Peavey Transtube Bandit 112.
Pedals: Digitech Bad Monkey.