As with sewing machines, the answer you get to this question from members will vary widely. Most of the machines sold are nice machines and will embroider well. It also depends on what you expect to do as well.
That being said here is my humble opinion.
I have had two - A Babylock Ellagio (which I loved and sold) and a Pfaff 2170. I wanted to be able to send designs from my computer directly to the machines. I also sold Vikings for a time. All three of those machine are excellent choices but so are others such as Janome, Brother and Berninna. The Babylock had incredible stitches, not picky about thread and a fantastic display while the Pfaff has great stitches, is very finicky about thread(only like the expensive stuff), wonderful sewing IDT, better hoop size options and connects directly to my computer (I have 4D software). I also bought this 2170 used off of Craigslist.
My recommendations: First think about these questions -
1. How much do you want to spend?
2. How large of an Embroidery do you want to do? Some machines will only do 4x4 (this is really small and does not give you a lot of area), some can do 5x7 while some do really large and are very flexible.
3. What sewing features might you want on the machine?
4. How do designs get loaded? Some machines can load from a USB stick some connect directly to a computer and some use a machine specific card - which will require expensive software to load and are pricey to purchase preloaded designs.
5. Will you want "classes" and support? It is best to make sure that you have a dealer around to answer questions, have service and cleaning as needed even if you don't want classes.
Next go to every sewing shop that sells any embroidery machines and ask to play (don't get sucked in to purchase until you play with a lot of them). If you have any questions about what I have suggested - fell free to PM me. Best of luck on this - they are expensive but fun