i must say that prefer going with those who can offer good support. that is you can get in touch with the network at will to discuss any thing, because at times it happens that you are not able to approch them on an urgent basis. for choosing of a network must consider the market they are focusing on uk/us/aus etc and if they exclusively belong to a particular industry type ex finance, gambling etc.
Try an affiliate program that offers a wide range of advertisers - Commission Junction seems to be good.
Join some good network, like cj or shareasale, they provide many information of affilate programs like epc, network earnings, trends etc. You can find right program there