"In general, what's your favorite/lightweight way to purify your water?"
Chris, you really need to outline where it is that you will be traveling. There are some places where the water is already very clean. Other places, you want to get rid of Giardia. Other places, you might worry more about bacteria or viruses (like in Nepal). You really want to assess the risks where you will be, and then you can select the best method of minimizing those risks. Where the risks seem greatest, you may even want to use two methods. It also depends somewhat on your own body. Some people are very sensitive about water, and it really needs to be clean. Others of us have been drinking mountain water for a long time, and we just need to be moderately cautious.
Thirty years ago, I used iodine for water treatment. By twenty years ago, I was using various filters that had to be pumped. Now I use a gravity feed filter. It seems lightweight and cheap and effective and quick.