What kind of plants do you have now and what are your plans in the future (plant wise)? As the other poster stated, if you increase the light, the other factors (ferts and CO2) need to be adjusted as well for best plant growth and to reduce to occurrence of algae.
My have a pair of T5 normal output on a shallower tank and it is fine for moss and crypts. More light demanding plants did not do well under those. I have been using a 30" Finned FugeRay over 20g long for about 10 months with good results. I have been thinking of possibly upgrading this; the BML option looks nice but pricey. The Finnex Planted+ might be ideal for my setup (currently using DIY CO2, PPS-Pro dry ferts, and glutaraldehyde).
One thing that lured me towards LEDs (aside from lower heating and operating cost) is not having the annual cost of bulb replacement with T5s. Potentially one could spend $60 for a 4 bulb setup annually. It adds up. The LEDs reported lifespan can be from anywhere from 10,000 to 50,000 hours depending on the brand/model. Even at 10,000 hours at 8 hours per day, that would be about 3.4 years.