I'd start off mentioning I am a big fan of C&Cs and owned a C&C 30 I for a number of years, a boat I still consider the best I've owned, and one I'd recommend over anything else in that size range.
Here are the phrfne.org ratings for these boats:
Sabre 28 198
C&C 29 I 174
Cat 30 180
(Do you really mean the C&C 29 II or the first model?, the II rates 171, not many of these around.). I'ver always felt the Sabre 28 to be a bit of a blah design, well made but not too exciting and it is disctinctly slower than the other two. The C&C 29 is a nicer design, but it is somewhat tender, many racers would add a 6 inche lead shoe to the keel and take some rating points to improve the situation. It doesn't have much room below for the length, especially headrooom forward due to the low overhead. The Cat 30 is a classic design, fairly roomy, solid, good sailor.
If sailing performance were the primary concern, I'd go with the C&C (or better yet a C&C 30 I), for all around cruising, you can't beat a Cat 30, and they are fine sailing boats. I don't think the Sabre has anything special from sailing charachteristics, I'd go with the faster performance of either of the orther two without a second thought.
Certified...in several regards...