USPS vs FedEX and UPS? Delivery problems HELP!?

I live in a residential place it's like vacation homes so we don't have mail boxes, we're supposed to rent a p.o. box but we usually get our mail with the club house person. When it comes to having packages delivered, do I give my normal address? I always do but most times I've had problems and my packages were marked as "undeliverable as addressed" by USPS. However, when I had the same package delivered again with UPS next day air I had absolutely no problem, it was waiting right outside my door on time. I'm planning to order online again and I wouldn't want the same thing to happen, but I don't know what the problem is. Is it my house? Or is it just that USPS is sucky and I should just pay a little more to have FedEX or UPS deliver it?