I use only COE 90 fusable glass. I'd say pretty much exclusively Bullseye these days. I prefer to work with transparents. Usually striker glass. 1.5mm thin. Striker glass has the distinct character of NOT really resembling the color and opacity the glass will be after firing. Much of it is colorless before firing, so if you're not careful you'll get your scraps mixed up with your clear scraps. I tape my striker scraps to the original piece (which is labeled) to prevent confusion.
I use lots of dichroic glass. I try to buy quarter sheets because they are simply more economical, though where I purchase my glass not every kind of dichroic is available in quarter sheets. I like to keep a selection of solid color dichroic, rainbow hued dichroic (Pixie Stix or Reptile, etc), patterned dichroic and textured dichroic glass available.
I buy mostly CBS and Savoy. Thin. Always thin.
I do alot of etching of dichroic glass. I use an ordinary Sharpie marker to stencil the glass and apply etching cream. The etching cream will not penetrate the Sharpie ink.
I buy all of my glass from Artisan Dichroic; http://www.artisandichroic.com/index.asp.
They only sell COE 90 glass. Bullseye and several brands of dichroic glass. A really great selection. Quarter sheets to 4"X4". Even the Bullseye is available in 4X4. Very reasonable shipping.