I just went through the same thing, I personally loved the Nomad solid because it read the lanes great and gave me a confidence I had not had with a ball in a long time.
I bought the 607A and it is a real nice ball but I didnt get that same warm and fuzzy I had with my Nomad. I always found the Nomad very smooth and versatile and the 607A doesnt seem to be as forgiving as the Nomad IMHO.
I also bought a 715T at the same time to replace my Virtual, which I love but it is very strong, much stronger than the Nomad.
After deciding I really liked both track balls but still looking for my benchmark ball, I bought the 505T as recommended by my pro shop( he wanted me to buy it before I bought the other 2 but I didnt listen..lol)....wow I LOVE IT! It is a bit earlier than the Nomad but very very smooth and it reads the lane excellent! I have had it for a month and have shot great with it on multiple patterns. I find it very versatile and after 6 -9 games it smoothed out even more. I cant say enough about this ball. I am throwing mine drilled 65x4.5x30 at 2000AB and could not be happier, I almost went and bought another Nomad before I bought this one. Im very glad I made this decision.
I am a 205 multiple league, multiple house average bowler. Shot a 6 game tournament set of 1396 last weekend without changing balls. Just migrated in throughout the day 10 and 7 and the ball just kept carrying!