Good question!
The answer has got to be a bit of both!
Firstly, you weigh up the cost versus the appeal of the girls. If money was no object, you would create your own party and book 3 well-reviewed stunners for 3 hrs and spend £1000+. If you have £100, the choice is between a 3hr party or 45 mins on a 1-2-1, the former appearing to offer better VFM.
Of course any girls you meet have to pass a minimum fuckability test which I would say the Phoenix/TLC girls pass muster, Em has a pretty keen eye for what guys like...but of course this is quite subjective and some girls will no doubt be more appealing than others, either in looks and/or attitude. I think it's possible that the more you party, the more open-minded you become to girls that aren't of your preferred type, but you will still look for a line-up which offers the greatest amount of what you prefer.
The problem you will have as a newbie is knowing which girls on any given day will have the appeal you deem necessary to want to meet. As the photos are from many sources and many have blurred faces, they don't always fully reveal the relative appeal of the girls. Some that have crap pics have turned out to be real hotties in the flesh. Others that have smooth pics have been a disappointment. Additionally, you can't infer anything much of a girl's attitude from her pics and that is at least as important as looks.
I think you're just going to have to take the bull by the horns and go! If you don't like it, it's not a huge amount lost. If you do, it could be the start of a new and exciting phase of your punting career!