In the end, it comes down to what works for you.
T5:
The good: Especially useful for growing multiple plants in a longer grow area. T5's are available in multiple wattage in various lengths to suit any need. They're relatively inexpensive. They last a good while, up to two years in many cases. (Even though they may look fine, replace at 2 years for spectrum as it will fall off over time.) The fixtures are flexible as far as keeping running goes. The ballast, wiring, and holders (socket ends) are all available at Home Depot type stores and take minutes to replace.
The bad: Not much. The longer fixtures can get pricey, but can actually be made from scratch and to order for about the same price or less as any "in the box" fixture. They (the home made ones) actually look cooler to me as well.
LED:
The good: low power usage for light produced is number one. You can get 7000 lumens for about 125 watts of power. That's hard to do with any other type of light. They also tend to run cooler than most any lighting fixture as well, which makes for much easier use in grow tents and other closed grow areas.
The bad: A bit on the pricey side considering the power you get. One can get much more light for the dollar with other fixtures. Also, they're disposal. Once the unit goes south, that's it. The entire unit has to be replaced for the most part once it's goes south, and when you consider that most have the life expectancy of about 3 or 4 bulbs of any other type, that's not a very long time.
Metal Halid / High Pressure Sodium:
The good: Pound for pound the best light there is for brute power bar none. Lighting levels that rival that of the sun, capable of burning your retinas out in a heartbeat and pound out 88,000 lumens in veg mode and 140,000 lumens in flower mode can be had for less than 250 dollars. It's simply the most powerful, cheapest, brightest alternative there is.
The bad: HEAT! Lots and lots of heat. Tons of heat. In any closed system (tents, closets, etc.) they can cause huge problems unless a great deal is put into circulating the air. Power usage. These things EAT power. Lots of it. Be prepared to see your power bill go up considerably, especially during veg stage when it's running 18 hours or more per day.
Compact Flourescent:
The good: Readily available everywhere. In a pinch, you can pick up bulbs and fixtures at Walmart. Reasonably priced. Low energy usage. Easy to build custom fixtures for custom setups with a short trip to Home Depot and minimal tools and know-how.
The bad: Limited in power options for the smaller fixtures. Very expensive in the more powerful fixtures to the point of redundancy.
All of that said, price is relative. Any of these types of lighting can be applied to any grow project. Figure out which one sounds best suited for your needs and go that way. In the end, the best one is the one that works best for your price range and situation. In the end, it's all light.