I've bought a fair share of Motiv equipment. I also buy from other companies as well, so I think I can give a fair assessment of my experiences.
I love my TZ3, but they are almost impossible to find. It's such a great light oil ball, I've used it primarly at one house and it's money, it was a limited international release and I'm glad I have one undrilled leftover as well. I wish Motiv could do a re-release, I think it would sell well.
I also love the Silver Recon, great ball to get through the drier or burnt heads and hits really hard for a light oil ball. It's very versitile and predicable, can play straighter or hook the lane with it.
My Thrash has it's purpose, usually when there is a little more oil, I love to play straight up with it, same powerful hitting power of most Motiv equipment. Drilled with the pin underneath my fingers, it's starts up a little earlier, but is very continuous.
I had a the orignal Cruel, shot an 815 with it, then it kind of lost it's reaction and I sold it. I was pretty great for about 5 months though.
Got the Primal Impulse last year and I didn't like it at all. Very over/under for me. Probably a bad matchup for my style, it was very hard for me to get a good roll on the ball. Pretty colors though.
Just purchased the Venom Toxin, rolled it a little last night, I think I'm going to like it, but need more time with it.
They have a great lineup, fits almost any style and condtion your looking for, but I also have many balls from other companies that I think complement my Motiv stuff.
Hope this helps!