Hi steveg, welcome to MR from a member pretty close to you I guess!
It might be a good idea to start with the Wiki E-Book reader matrix -
here. I personally have a Sony 505 which I love, but the options have certainly changed and expanded since I bought that.
Also, the best advice I can give is to try to get your hands on the ones which you think you may like. Nothing beats a hands-on experience and, if I've learnt one thing from this forum, personal preference is very important.