Without knowing your budget, my simple advice is don't go cheap. Having said that, here are a couple worthy mentions. The purpose-built EFBs have screen hacks that allow for extra bright and extra dim settings. This is important if you are serious about using it. Also, built-in Bluetooth is a must, IMHO.
On a side note, we're looking at adding
WxWorx to our EFB, as Jepp has just released a software update that displays it on Jeppview.
Let us know what you end up with and give a little review.