There really is no way of saying whether the country would have been in a better or worse position than it is now if Labour had been in power for those 12 years, given it is hypothetical and it just is not possible to compare. An individual's viewpoint is going to be driven by their own politics so if you're left wing you'll think it would have been better and if you're right wing you'll think it would have been worse.
Historians love counter factual scenarios, and almost every occasion, counter factual tends to result in convergence with actual events in the long run. Given most political decisions only tweak around the edges, certainly in respect of the economy, my view is that we'd probably be exactly where we are today.