Which is better is all relative.....it is a matter of opinion. I do not have a Zire 72 and I have not owned one. I do have a T5.
In looking at the details of the two different PDA's here are the surface differences:
Zire 72
voice memo
digital camera
hi res color screen
32 mb storage
palm os 5.28
312 MHz Intel processor
price: $249
T-5
rotating hi-res color screen
256 mb drive memory
palm OS 5.4
416 MHz Intel processor
price: $349
I suppose your decision all depends upon what you are looking for in what you need your T5 to do for you.
Carol