hi rabt, and welcome to mobileread. you've come to the right place for advice about choosing a device that meets your needs ! i recommend you take a look at our
wiki (notably the excellent
ebook comparison matrix) to get an idea of various technical specs, and also take a look at some of the other discussions which might help you out.
since you say you read a lot of science fiction, have you heard of baen books ? they sell ebooks at very reasonable prices in multiple formats and without drm. there are also lots of other ebook sites, fictionwise and books on board to name two. regardless of the device you choose you're never limited to one bookstore. and, we've got thousands of free public domain books right here in our ebook uploads section (click on the "e-books" link in the blue nav bar at the top of the page) formatted by our members.
i'm going to move your post to our "which one should i buy ?" forum where you'll get more help.
choosing is the hard part
but i'm sure you'll love whatever device you end up with.