I have been doing machine embroidery for several years. There are a few things to consider when you are trying to choose a machine.
How big is the biggest hoop for the machine? Is that big enough for what you want to do?
Does the thread change automatically? or do you have to re thread manually for each color change?
How do you get designs from your computer to the machine? Cable? USB? Card?
If you don't already know how it works, are there people (online or in person) who can help you with that specific machine?
How much do you want to spend?
My first machine was a Singer XL6000 and I loved it dearly. Until I wanted to sew larger designs with lots of color changes.
Last fall I purchased an Avance commercial machine and it is soooo much better. (but it cost more too!)
Another thing to consider is what software do you want to use?
I like Embird. It is affordable and you only have to buy the sections you need.
Embroidery Machine Designs
To view embroidery designs as thumbails
https://www.secretsof.com sells Embird, Embird Tutorials and designs
Embird Yahoo Groups
CAS - Custom Apparel Startup
Singer XL6000 Yahoo Group
Avance Embroidery Machine