In the compact camera range, with the latest cameras,these days, there are mostly the same, all have pro's and con's, and produce very good images, under general conditions. Lots of people have good and bad exp with the same brand/model of compact digitals.
You could read articles all day long, and still not get the "best" one for your sister.
First thing is suggest, unless shes on a world trip leaving tomorrow; find more about what she wants to use it for. look at every day and styles she likes, then look for those features. Knowing what types of pics she wants to take, you can choose a better fit, in getting a compact, that would suit her needs.
My choice, would ensure its got auto modes, and manual adjustments.
I choose Casio Exslim EV8, for one main reason 8x optical zoom, on 10mp camera. even over 12mp models available.
Dont expect the same results from compact camera, compaired to high end DSLR. That dosent mean you cant her great photos's but you need to understand what the portable camera is able to do.
The most important advice i would give is really learn what the strenghs and weakness are on the camera she buys, take all sorts of shots, lots and lots under every condition. you can adapt how you shoot if you know how a compact will behave under difficult conditions.
I bought Nikon Coolpix to start out with and I think it's ok. All of the photography in my gallery is taken with it. It's a good compact camera but some editing in Photoshop is required to get better results.