Depends on what you want out of your university experience really...
I'd argue Manchester and St Andrews are very similar from a reputation standpoint, however in the last few years, St Andrews has increasingly done better in the more competitive employment sectors - finance, consulting etc (especially in the major firms, Goldman, BAML)
That said, the nightlife and social scene is obviously 10x better at Manchester than it is in St Andrews so if that's your main point, go there instead