When it comes to my own art I prefer the former, but I like both nearly equally when it comes to just viewing.
I don't think nihilistic necessarily means depressing. Personally I have an idealistic nihilist view on life. I don't think that life has any real meaning, so we can make of it whatever we want. That's not a bad thing to me. Also, both. Both is good. I like art that is dark but also knows when to be upbeat and light. Art that can be dark one moment and humorous the next. However, sometimes it's nice just to see something cheerful, inspiring and perhaps a tad idealistic. Frankly I think they're two sides of the same coin. For instance, when you see a small bug and it almost looks cute but then you see it up close and consider the fact that if they were the size of a small dog it'd be terrifying. A lot of things are cheerful and morbid or depressing. Take butterflies for example. Beautiful flying gently in the breeze. Not so pretty feasting on the corpses of rotting animals. I like exploring both sides. There's a duality to it.
I can see value in both actually. In many ways it's a matter of perspective and it also relates to mood and emotion. For me, it's about quality rather than style.
