That depends on the amount of stuff you're running, and how much you care about the UPS working. If the answer to both is "very little" or "not much", I'd take the Pi setup any day.
It also depends on how often you expect to lose power. If that answer is “somewhat often” or worse, then even a minor annoyance can be worth avoiding. There’s a reason laptops used as a server were known as “California servers”. (aka a server with a built in UPS)
