If you go by the strict definition of 'UFO', then of course they are out there. There are a lot of unidentified objects in the skies every year.
But, if you mean UFOs with extra-terrestial life forms, I also do believe they are out there. Just ask someone like Bob Lazar if he has seen an ET UFO up close.
The universe is just too vast to believe we are the only forms of intelligent life. It's also naive to think that we are the most advanced tecnologically speaking. We have no idea what is out there. There could be intelligent life forms in a distant universe with millions of years on us in terms of evolving. Heck, we ourselves could even be technically 'alien' and not native to earth. If you don't buy into creationism, Darwinism, the Big Bang theory, or the like, what's to say that some other life forms didn't arrive thousands of years ago and decided to have a colonization of themselves on this planet? Far fetched? Maybe. Impossible? I can't definitively say it is. All theories can have holes punched in them.
The truth is out there.