The Brother CS6000i is a good machine, a neighbor bought one for her daughter, got a great price on Amazon so I would check there. That machine came highly recommended to me by a gentleman who quilts who purchased one for himself, then a year later purchased one for his daughter, he liked it so much.
The Brother XR-9000 is almost identical to the CS6000i, it just has a few more stitches and the warranty is slightly different.
Janome, Kenmore and Brother all share the same manufacturer so you will find there is little difference between these machines and the stitches they offer.
The Shark EuroPro Model 9110 was also produced by the same manufacturer. This machine was sold at Target around 10 years ago. It's an excellent machine, I bought one used for my classroom. I would recommend it if you come across one, they are hard to find.
You can check reviews on various sewing machines on this website:
http://sewing.patternreview.com/