This has probably been done before, but I made a poll on which Half-Life Gearbox expansion is the best.
You can vote here
You can vote here
I was really fond of Opposing Force.
The weapons were pretty cool and the fact that you’d see Gordon here and there was awesome.
Opposing Force had some really cool elements but I really dug the oft forgotton background character feel of Blue Shift. It also had some nice little puzzles too.