Glass for fusing
In addition to Spectrum and Bullseye, Uroboros manufactures fusible glass, and Armstrong has fusible float. Make sure you are combining glasses that possess the same COE. Bullseye is 90COE, Spectrum is 96, I think Uro does both, and the float is 82.
For variety of colors, Bullseye is your best bet. For cost and ease of cutting, you might prefer Spectrum (and they have a fairly wide color pallet too).
Jester’s Baubles Fused Glass Designs