For initial outlay, tubes are still cheaper.
For a tried and tested answer, tubes are well understood.
For lower running costs LED's are generally cheaper in both power use and replacement costs (although some cheap LED's are fairly shortlived).
For control over light types, LED's are rapidly gaining the high ground. Cheap sets won't compete with a fairly cheap and simple to arrange T5 rig, but the more expensive LED options can be perfected to exactly the colour types that people want, and some can be tweaked to the users needs as well.
Overall, for power usage, you'll only really notice if you have a lot of light, so it's really more relevant for high energy planted tanks and reef tanks, but is increasingly an issue if you pay the electricity bill.