I like both, though I prefer Strike Zone. People complain of the pauses between strikes, but I use that time to do the following 'Cathe' moves:
Hammer-punch lunges
Lateral skates
Sumo squats
Power scissors
Jumping rope in a 'z' formation ala Kick Max or High Step Challenge
Plie jacks
Plyo jacks
or just a boxer's shuffle if I'm tired after a particular 'strike.'
I wish In the Ring's med ball segments were tougher. I wish she'd put Hi/Lo Knockout's 'knockouts' in In The Ring (or something of a similar intensity). If you do get In the Ring, you can try use a 10, 12, and 15# db instead of a medball, as I find using dumbbells to be more of a challenge. That said, I do enjoy both In the Ring AND Strike Zone.