Depends on who you ask around here. Personally, I use a light with UV. Why? Our first gecko wasn't growing as fast as we thought he should so, after reading all the documentation online arguing whether or not leos needed UV, I figured it was a small investment to test it myself. Three days of his new light and he was eating like a champ. We certainly won't use anything else for our pets now, but this is because of our direct observation. I can also say that I think it may have helped us grow an almost 10" long female in 7 months.
Allow me to add one little thought about fact, leos aren't strictly nocturnal. In the wild they often hunt at dusk and dawn and would be exposed to sunlight at those times. We have observed this is captive leos as well... they sometimes take a gecko inspection lap of their territory before the light goes out. We have even seen them "bask" a bit, as shown in the baby picture below, the light is her own. So it is a preference, I'm sure those here with rack systems will have the counterpoint to my experience. But as far as taking the leo out in the sunlight, then I completely disagree... especially since I live in MN. Keep the leo indoors, they aren't prepared for the bugs/pesticides/whatever is out there. Just use a light.
Here she is basking her tail, a normal event for her when she was younger.

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0.1 Albino Leo Gecko
0.1 Crested Gecko
1.0 Dear Boyfriend
Departed: Harvey and Spock