I use a Light Rider bridle on my horse. It's like a modified side-pull, is simple and effective, gives clear signals and gives control without being harsh (meaning it's only as harsh as your hands are, there is no leverage it works solely on the nose). The only time when I felt I didn't have the control I would have liked was when I was galloping my horse up the hill, but then I get the same response in a bit, we just need to work on our transitions.
If you're going to go bitless I really like this bridle, over Dr. Cook/ Nurtural cross-under types. Light Rider Bitless Bridle