I've had trips on both as well as a host of other Aggressor ships. Personally, I would go with the Aggressor. Caviet however is that of all the Aggressor boats I've been on, the Galapogos Aggressor crew was the absolute laziest. Keep in mind that this was in 1999 so I am sure the crew has changed. With the PH boat, they ran out of food and had to make a pit stop, wasting valuable dive time to get more and to make matters worse, they ran out of rum. At that time, the PH boat had only been in the water for 2 or 3 years but it was coming apart. The shower drains rusty and bent so you had to be careful about stepping on them and cutting yourself. The photo tables were horribly warped and so on. However, the crew were just fine and friendly.
All of my other Aggressor boat experiences have been, for the most part, very good. My favorite is the Okeanos Aggressor which I have been on 10 times, and the Tahiti and Truk Aggressor.
Steve B)