I've beta tested:
EQ2, Eve, Horizons, um... a few other games that I can't remember at the moment... The Imagination Network!
LOL they fed exed me the 15 3.5 disks that I needed to update it every time they changed it. Ahhh How I miss my 5400 baud modem...
Um... my head won't remember... I did not beta test eq1 but that's mostly because my computer I had at that time could not play eq1.
But I played eq1 from 1999 till around 2002 when I just petered out... I came back now and then, but then I got hooked to eq2, even though some people don't like it and thinks it's too cartoony (points at Aredhel) but that's not the point nor the question.
I've beta'd quite a few non-online games as well.
I sincerely hope to beta Vanguard, and will give it the same attention I did to all the others.