Its whichever you want. I like the subarus but the skylines are pretty sick too. If I had the choice I would go with the skyline as you dont see many around, and you would stand out from the crowd, thats for sure!
go for the nissan ,I have freinds that own these and they have a good reputation for parts and a good history of reliabilty,the subaru is ok but a littlle borriing and over priced.
Here in NZ the insurance for Imprezas (amongst other cars) are ridiculous, especially if you are only on your restricted or your learning licence. I don't know about the situation with you. Me personally, Skylines I like a little and look a little better than the Impreza. Just me though, coming from a teenage girl... so what do I know eh?