On Peek Wallets vs. Impression Devices...
I go for impression devices hands down. I've never liked peek wallets. I don't care what explanation you have for taking the spectator's business card in your hands and putting it inside your own wallet, but I think that's one of the most absurd things I've ever heard of. Any card magician who did anything remotely equivalent would get laughed out of the building. I don't know how so many mentalists can delude themselves into using such a prop. There are simply far too many disadvantages, which take an extraordinary presentation and performer to get around - and even then, I have my doubts. Why you would want to handle something they've written on is beyond me. Even if you didn't handle it, why you would want to insert it into your own wallet leaves me at a loss. Impression pads are cleaner and more versatile.
As far as which impression pads to go to, I would encourage you to do your own research. Each person has their own preferences. I used Universal Impression for a while (i.e. the predecessor of Psypher). I've found that it does what it needs to perfectly, but just isn't right for me. Different pads use different sorts of gimmicks, and you'll need to play with them to find one that suits you. There's no "best" one. Mentalists will swear by the ones they're using, but there are many different ones in use. As I just mentioned, UI works perfectly, but is not my preferred one.