I used to use GW's green stuff... but they are way too expensive. I switched over to GaleForce Nine. The stuff I have comes in two separate tubes rather than a strip, so there is no wastage where the two would normally touch.
I use GaleForce aswell, ony one I ever had. Can't really compare it to anything else but I think it works just fine. The epoxy has a tendency to stick to the side of the container so wrap them in cling film easier to get it out
Same here as well, it's always worth getting the packs when the two parts are separate from one another and can be sealed to keep dust off them.