I am looking to buy my second investment property should is a best to start in a rural or city area ?
The easy answer is to say buy wherever the numbers make sense! Personally, I prefer buying in or near a city because I feel confident that there will always be demand. Does't necessarily mean it has to be a metro though.
Which market are you looking to invest in?
What returns and areas so you want to focus in? Condition of home? Rehab or turnkey condition? Tenant class? Appreciation you'd like to see?
I would buy in a city area just so that I can get the property to appreciate and be able to increase rent on a regular basis.