I've spoken to over 200 psychics on PS and over 300 on Keen, so here are my two cents. Ultimate outcome predictions are yet to come, so I can't comment on the psychics mentioned below.
If you do your research, Keen has some decently priced psychics, but reviews are all over the place and there is debate on whether or not reviews are deleted so that might make it difficult to find the right psychic.
I like PS a lot better. If you don't know who to read with, the chances of connecting with a better quality psychic are higher on PS than on Keen. Found that out the hard and expensive way. Though the prices are bit higher on PS, I find it easier to control spending with their system.
And just some technicalities to point out. Keen doesn't let you leave feedback after two weeks, so a lot of the psychics will go--well, give it 2 more weeks. I wanted to go back and leave some feedback on the ones who used the 2w time frame, but found that I couldn't...coincidentally. So if you're going to leave a review, leave it asap haha. PS gives you a three month time frame.
I tried and no longer even touch AskNow.