I can think of six reasons in favour of a country school, but only half a dozen in favour of a city school.
Seriously, start by thinking about what you want out of the CPL. If its a career, then a "name" school with credentials may have the edge. Also, where are your skills weak? If its CTA procedures, then that points to a city school. If its shorter strips, crosswind, etc then think about a country strip.
Above all the most critical thing is doing it with an instructor with whom you have a good relationship, who you respect and operates at the level of discipline & professionalism to which you aspire. You may also be looking to this person to give an insurance company a reference on your flying. So, a CPL instructor needs to be a reasonably heavy hitter. Especially if he/ she doesn't have a brand like Oxford behind them.
This is an opportunity to do some deep thinking about your objectives, strengths / weaknesses and make a strategic choice.