I bought an N/A R33 for my third car and couldn't be happier, mate. Unless you're wealthy don't go for a turbo skyline, not only do companies gouge you on insurance, and with petrol prices rising so quickly these days pretty soon turbo cars will be unsellable relics... go the N/A R33 and it'll be fast enough for your needs, safe enough for you, and won't cost an arm and a leg to run, maintain or insure. To give you an idea of my fuel efficiency it costs me just over 10 litres to go 100km - the same as a lot of my friends 4 cylinder cars.
People on here say they are crap, but to be honest it depends on your priorities. If you're willing to sacrifice a lot just for the extra speed, then go for the GTST. Otherwise a N/A R33 is a good choice.
Lachie