It depends very much on the overall shape of your foot, Stephen, and on different manufacturers' lasts. The latter can vary in shape almost as much as the human foot. I suggest you find a good, specialist stockist who can measure your foot properly and allow you to try on several different brands. When you find a brand that's comfortable for your bunion, remember it and ask for it next time.
& for immediate relief, do what my mum does & place a thin piece of sponge between shoe & bunion & inside your sock ( thin circular make up sponge is ideal ) available from most chemists!