I use Purigen in nanos, nothing in tanks larger than 10 gallons. My only reason for that is Purigen doesn't last very long in my larger canisters before it's "saturated" and I don't clean accordingly, making it kind of useless.
I have also used a UV over the years. I rarely keep it on. It's great to plug in for a day for super clear water when you are having people over. I likely wouldn't buy another.
At this point, I could care less about chemical filtration, I just use it because I already have it.