I'd keep the Rover.
Although its a shame its not a turbo, as there would be no desicion to make then!
It may be old, creaky, and looking a bit early 90's but at least the old girl probably has some soul. Over a bland, generic, jap clone.
How about some pics of the two cars? Maybe the new Micra does actually look quite smart? Im struggling to visualise a Micra, its not the sort of car I can really ever remember!! (or would need or want to)