The shoe that I always realise I need, but never seem to have is the flat closed in shoe. There are times when a boot or a heel either doesnt suit what I'm wearing or is inappropriate for an occasion, i.e. running around doing errands or attending a relaxed function.
Personally I find ballet flats a little too girly for my liking (say no to the bow!), brogues a little too androgynous and slippers… you must be joking.
If you're as particular about footwear as I am and you're reading the above and get what I'm on about, then hopefully you'll like some of these selections I found!