I would not specifically buy anything fluorescent, metal hallide, etc. You have to change lamps regularly because their radiation output fades and quality lamps are expensive.
Go with LED. Tons of options out there for a 36" LED aquarium strip light.
If you have the T5 fixtures on hand, by all means use them, especially if they're older, better made stuff. Problem is like said, today's replacement fluorescent tubes suck compared to the ones made years ago.
What lights should I get then? All these lights are only like 20 watt and that’s like nothing compared to price I’d have to get like 5 of those which would be like 200$ compared to a 2 bulb fixture with lights would be like 60$
The wattage rating means nothing for your tank. All that is, is a measure of how much power the fixture consumes. Way back in the day the old watts per gallon was a rough estimate that applied to fluorescent fixtures only. LEDs consume a fraction of the power that fluorecents did, that's why you see the low wattage specs on LEDs
Like you said, lumens in your point of reference now.