I don't know any altcoins that are better than Bitcoin. The question is, better in what? Are they more decentralized? I don't think so. Are they more reliable in the long run, or more secure due to a strong community and high market capitalization? Not really. Are transactions cheaper and faster? Perhaps they are, so that could be an argument.
Bitcoin is strong, the market cap is huge, it's a PoW currency, and it's been #1 since it appeared. That's why I choose Bitcoin over any other altcoin.