"I tried (or know someone who tried) the low-carb thing, and once I started eating carbs again, I gained all that weight back?"
Like the low-fat people who go back to eating fat again once they lose the weight? Low-sugar? No red meat? Whatever you decided to eliminate and then start eating again?
Come on! If you eliminate something from your diet and start eating it again once you meet your goals, of course you are gong to gain it back. If you start exercising and then stop exercising once the weight is gone, you will gain it back. Especially if you go back to eating those items in the same ways that you ate them previously. Going on a low-carb diet doesn't mean going without carbs forever. In most plans, you will eventually eat them again. However, they won't be as prevalent in your diet as they were in the past.
Whether you choose to go low-fat or low-carb, you have to do something that you feel you can complete consistently. That's how you will achieve the most success with your diet.