I have to say that the main reason we buy is because I hate renting. I have 4 kids and 2 dogs, do you know how quickly they can damage a house (I'm talking accidents here, not willful destruction)? And then I get all hyper because it's not my house they have damaged. When we buy, we just fix it. In addition, I get tired of living with other people's decor. I want to paint and decorate and remodel to my taste. We own a rental property, and the tenants are constantly griping because they don't like the carpet and paint colors. Too bad, it's not your house! I hate this feeling of maintaining other people's property, and never being able to make improvements because it's not mine.
So, that's more of a heart decision than a financial one. There are financial benefits, though. We have made a lot of money buying and selling houses over the years. Our rental has been a great investment, and the house we are currently living in will be, too. We bought near the bottom of the market, and prices are already going up quickly. You have to pay to live somewhere, you might as well live somewhere that will make you money, too.
Also, with interest rates so low, you may be better off putting your 20% down in to a Vanguard or some such than on the house. You will probably get a higher return that way. We chose not to put 20% down when we bought this house, even though we had it, and invested the money instead. My husband has a 10 year contract here, and we plan on staying after that as well. We will probably live here beyond retirement, and by then, the house will be paid off. Equity doesn't matter to us, we don't need to take out home equity loans, and don't plan on refinancing because the rate is so low, and we have no trouble making the payments, so having 20% down didn't matter.