Having stayed at both:

Room: they are comparable, but I think without a SUA you will have a better luck getting suite upgrade in Aviara vs Alila (Alila I used a SUA, Aviara I gambled on comp upgrade and got Pool Suite)
View: Alila's beach view is unbeatable if that's your thing, while I think Aviara is just the Pool view, a Courtyard view, or ... nothing
Breakfast: Alila is better, but I feel Aviara isn't too far behind (pure food taste wise)
Service: this is where Alila really dropped the ball for me despite being a cat7 I felt breakfast service was slow, FD service was slow, and overall just felt off. Aviara felt much well staffed and well trained
Amenities: Much more kids in Aviara (it even has a kid pool after all), but also the pool is bigger with heated pool and jacuzzi area, Alila felt pretty small and I wasn't sure was the pool heated or just warm from that day
Finally, Aviara despite being a PH its Golf Resort nature overshadows it imo, while Alila's presentation feels like a cat7 (definitely not its old cat8 though)

Personally if you can live with expecting mediocre service, Alila is probably better. PH is an overall better hotel but I don't find it as unique as Alila.