missypiano
I can only reiterate what organ_dummy has said. Editions can vary enormously, especially in terms of the editorial markings (fingering being a significant example). I find that the process of choosing an edition that suits you is often a matter of trial and error at first, and I have often had to buy several different editions, only to find that the first one I got hold of turns out to be the most reliable and useful

. But you should find that, with experience, a particular publisher starts to become a favourite.
I think it's useful to bear in mind the following when weighing up the options:
the introductory section (background information on the work(s), the composer, the first perfomance, hints and tips on interpretation, and so on);
the extent of (or lack of, in the case of
urtext editions) editorial markings;
the page layout, and where page turns fall;
the reputation of the publisher;
the price;
the date of publication (earlier editions may be out of step with current musicological opinion, but can also provide interesting details which may be omitted in later ones);
this list is by no means comprehensive, and I'm sure I have left out many other important considerations, which fellow forumites will gleefully pick up on...
In organ_dummy's case, its the highly rated 'henle' editions which appeal the most. I too find them refreshingly straightforward, as are Barenreiter.
Good luck
denmark
correction 'perfomance' = performance