I'll join in. Made many a dollar and won many a tournament with:
Ebonite: The Nitro series, the Matrix series, and the Apex series. The Nitro was a great alternate to the Hammer, but when Ebonite brought out reactive resin through the Turbo/X and Crush/R, they caught everyone's eye, but the Nitro/R and Nitro R2 took off immensely, and a few companies couldn't keep up.
Honorable mention here would also be the NV series. The NV was okay for me, but the Total NV and Complete NV were so good I ended up getting 2 of each and kept them at the ready for when I needed it; the Complete NV joins the Blue and Blue Pearl as trophy (read: honor score) balls.
Hammer: The entire original Faball line. There is a reason why up until recently, the Blue and Blue Pearl were still in my bag. as 300/1100 series balls, they now enjoy a trophy retirement.
While the Widows have already been mentioned, I'll go another direction and throw in the Blood series. The First Blood and Cold Blood were phenomenal pieces for the early 2010s, and when they brought out the Gas Mask Clear in Japan, EBI finally had the good idea to make a plastic ball with core, in the BW Spare, but more importantly the True Blood. Those three in that series were great for me.
Brunswick: I didn't throw much of them, but a longstanding series that was great that I did get to throw were the Zones. I can't remember how many of those balls in that series were made, but I want to say that there was a good 160something of them made since 1995 (still being poured today).. Throwing the Command Zone Arc and the Riot Zone got me the most success from Brunswick (pre-BoB).
There are more, but I'm also trying to limit this to series that had more than 2 balls in it, which rules out something like the Quake, Pulse, Optyx, and TPC series.
BL.