I have 2 Brother and 1 Janome machines. They are computerized and circuit boards do go out. It is very pricey to get them fixed....$400~$600. I had a big box Janome machine I loved but it has quit sewing. My little Brother (big box) has a nasty habit of pulling fabric in crooked but it's still sewing. I have learned how to pull a bit to the left to keep it from fudging to the right.
Test drive any and every machine you like. Can you thread it easily? Does it have a free motion foot? How about a 1/4 inch foot? Can you adjust the needle to the left or right? Does it have a large throat? Do you have service locally and/or a warranty? Check out what the stitches look like. The Janome I bought has the best stitches, but the Brother is still working.
Good luck!