I have had best success with my hummingbird feeder. I have tried a few different designs, but the one I like best is the HummZinger, which you can see here. It's easy to fill without spilling or dripping, easy to clean, and quite successful at attracting the hummers. It has a built-in "moat" which you fill with water to stop ants from invading the feeder. Every time I clean and refill the feeder, I find a few dead ants in the moat, which proves it's working. I don't think the hummers really mind having ants in their feeder, but why attract them?
To make fluid for any hummingbird feeder, mix ΒΌ cup white sugar with 1 cup warm tap water. Don't bother adding coloring. The red color of the feeder will attract the hummers. Empty, clean, and refill the feeder at least twice a week.