I had the AFR heads on my 351W and was really happy with them. I didn't have to worry about PTV clearance (you can still pick yours pistons, so no big deal) and they made great power in my opinion, but then again it was my first old school pushrod V8.
That said, my understanding is that the AFR needs a really high compression to reach their maximum HP. The Max HP on AFR would be a little more than TW, but you need to be at least 10.5 to get there. If you are going to run anything under that then the TW will supposedly make better HP.