It really depends exactly what you want it to do. For example I'm a quilter - I use very few stitches so it's not worth me paying for lots of fancy embroidery stitches. I do need a machine that can cope with bulk and heavy-duty sewing though. A garment maker or embroider may have different requirements.
I would recommend finding a specialist sewing machine shop and talking to them about your needs. They should let you have a go on the machines to see what you like - take some fabric with you of the kind you most often work with. If they won't let you try the machines, or they don't know what they're selling, find somewhere else. The shops that do repairs / servicing are often good as they can tell you which machines they have to repair the most.
Don't rule out second hand machines either - again, the specialists may have reconditioned trade-ins. Often you can get a better machine at a lower price.
Have fun - and don't rush your decision.