They are both very good systems. The Ortronics is likely to cost less.
We wired our Lab with all Avaya Cat5e (Cat6 hadn't been ratified yet). The cabling is excellent. I'm a little disappointed with the panels, especially the multimedia panels (several of the module retnetion clips broke with very little use).
I'd say get the vendor to bring in samples of each panel and info outlets. Choose the one that you like the best and go with it.
The Avaya cabling probably has a little more overhead with the specs; for a professionally installed system (with certification documentation), it isn't going to make much difference.
As I said, both are very good products ... you could go with either and have an excellent system.
FWIW
Scott