So starting a redesign of a site and was wandering if anyone could advise?

 

There are obviously plus points for either way, but which is best? Separate stylesheets would be my guess, but I am open for opinion.

 

Also what is the best way to do this? Keep it minimal, design it like an app?

I'd go responsive. It's a lot of fun but you'd still need CSS rules either way to get the browser to detect your screen widths. If you're going responsive. Decide right away, otherwise you'll get into a real tangle when trying to responsinate (i word i made up ) a website you previously designed purely for desktop. Mobile devices might pick up errors when trying to render them.

I'd be inclined to write a separate stylesheet for mobile users, but design the desktop site so that it's responsive enough that when mobile device detection fails, the site is still usuable.