For most photographers, this comes down largely to personal preference and the quality of the tripod rather than one lock type being universally better.

Common trade-offs:

• Flip/lever locks: easy to see and operate, and some people find them easier to grip in wet, cold, or worn conditions. Possible downsides are extra bulk, potential snagging, and on some models they can close with a loud snap.
• Twist locks: often feel sleeker and less bulky, and some users find them just as fast or easier to operate one-handed. Possible downsides are that they can be harder to grip when wet, cold, or if the tripod gets older and less smooth.

In practice, both systems can be quick and reliable when well designed. Poorly made examples of either type can be annoying.

So the main considerations are:

1. Which feels more natural in your hands
2. How it performs in the conditions you shoot in
3. Build quality and durability of the specific tripod

If possible, try both in person. A good tripod with either lock style is usually a better choice than a mediocre tripod with your “preferred” lock type.