My current reader (Sony PRS-600) is coming to the end of its life!

And I just don't know which one to go for now.
Whilst I am tempted to go for the Kindle as everyone I know has one, I have far too many books to go through the hassle of converting them to the correct file format, plus my local library doesn't rent out Kindle books.
I'm based in the UK so limited somewhat is what I can buy and also it has to be worth the hassle before I buy overseas. I've looked at the new Sony plus the Kobo but there is just too many on the market to make an informed decision.
Any advice is gratefully received!!
Thanks