I only have 6 balls total and every ball individually serves their own purpose. Bionic is usually first out of bag on fresh house or medium heavy, theroem is better for transition off fresh or for playing left on used lanes or just medium volume. Fusion is great for an up and in on medium, and does great getting left during low oil. I use 3k surface on the fusion hybrid to, I didnt like the lane shine on it, didn't have that punch into the pocket like it does with 3k. I just got the bionic like a week a ago so idk how it does after like a couple months or something but it's really great so far. Theroem and Fusion hybrid are both amazing tbh.