I think ultimately you want to be on ABC. I would guess that the Notre Dame and Clemson games have a good shot at that. When it comes to the ESPN/2 games, it is better to be on ESPN/2 than not to be. In which case a Friday game guarantees that. Where as a Saturday game you will not know until 2 weeks out.
As to Friday vs Saturday ratings, I think it depends. Who are you going up against? The Fox games (both Friday and Saturday) are going to steal a bunch of viewers being on network TV, even for a poor matchup. And a good matchup will hurt even more. But all things being equal, I think Friday would do better.
Looking at last year's ESPN Friday games with an ACC team compared to other ESPN/2 games (no ABC)...
Week 9
Louisville/BC was worse than the 730 TH (SU/Pitt), 7 (FSU/Miami)
Week 8
FSU/Duke was worse then 330 (ND/GA Tech) and better than 7 TH (BC/VA Tech)
Week 5
VA Tech/Miami did better than 7 (Stanford/Clemson), 4 (UNC/Duke)
Week 4
Stanford/Cuse did better than 7 (Miami/UCF), 7 (Cal/FSU), 330 (GA Tech/Louisville)
Week 2
BYU/SMU did worse than 330 (Cal/Auburn) and better than 7 (UVA/Wake), 1200 (Pitt/Cincy)