Whey is fast-acting.
Perfect for after a workout, but not such a good idea the rest of the time.
Causes huge insulin spikes.
Egg protein doesn't mix very well.
Casein is often preferred to whey because it's slower digesting, causes less of an insulin spike, and it's been shown in some studies to promote muscle growth to a larger degree than whey.
A chicken breast is a great option. However, it's hard to consume two chicken breasts (about 40 to 50 grams of protein) every three hours.
When possible, eat whole protein (such as a chicken breast), but when it's not possible or convenient, drink a whey/casein blend (except for after a workout, when you'll ideally want some whey).