Size 14/16 is attractive to many. I'd say the biggest determinant of physical attractiveness for most people is if someone looks healthy, and it's hard to define exactly what that looks like. Different people look healthy at different sizes.
If your main goal is for the majority to perceive you as physically attractive, I'd advise you to aim for health.
Cut out added sugar completely, and eat things like fruit, vegetables, nuts, meat, fish, dairy. Eat until full, eat again when you get hungry.
Try to exercise regularly, without pushing yourself to the point of injury.
Try to get enough sleep every night, minimize stress and don't take harmful substances.
If you do all these things, your body will end up being at optimum health, and you will be the correct size. Everyone's correct size is different, which is why I can't give you an exact figure.
If you're asking for personal opinions, when it comes to women, I'm generally attracted to around size 10-12 (UK sizing). I believe I'm in the minority though, other people are a lot less fussy, and my other 2 paragraphs offer more well-rounded advice.