3, 5, 6 and 7 were by far my favourite series, with BB10 being the only other series i liked.
I joined DS early in BB7, and that was the series i got most inolved with, so that series will always be special to me.
BB6 was brilliant, but pretty dark and uncomfortable viewing at times.
5, was also brilliant with probably the strongest cast without any real weak links, and overall probably made for the best hl's series.
However, i don't think the live feed was as good as 3, 6 or 7. I actually prefered the live feed of 3, 6 and 7 over the hl's shows.
Overall though BB3 is my alltime fav series.