I'm a dressmaker designer, and I'd suggest you try machines before you buy, just to see if you like them. I have a basic Brother (£80 ish) for students to use, as well as a brother nx600 and an even higher spec machine that I use daily (Janome mc6700p).
The basic brother is lovely. A really solid little machine that, in all truthfulness, I could actually do most of my work on. The fancier machines are smoother, quieter, more luxurious, but they still just sew at the end of the day.
I'd personally go for an easily available brand, if only to make servicing, replacing parts and buying accessories and presser feet easier. You know they'll fit and work.