Price within your limits & financing. If you realistically think you will quilting for paying customers then you can raise your price limits. If you aren't sure, don't.
What type of support does the company have. Example: one of my home local dealers want me to take the machine to them for service, however if it is a problem with the wiring or connections to the trolley/carriage then they wouldn't know. To come to someone's home is very expensive! Also they seem to have problems keeping techs.
Do you want a computerized system or not. Can you affordably add it on later?
Many machines now have laser lights for pantographs.
What size will fit in you studio/home?
Personally I didn't like the Qbot.
I have a HQ Avante now and love it even without a computerized portion. Miss the HQ16 but this is better for me for now. I have excellent service from a HQ service person not affiliated with any store [the store closed end of January & HQ wants him to still cover the HQ's.] I have gotten great telephone assistance from HQ, enjoy the educational webinars/videos.
Enjoy the journey and take your time.