Formal:
* "God speed you" (God grant you good fortune)
* "God save you" (May God protect you)
* "Welcome" (Welcome to you)
Informal:
* "God ye good morrow" (May God grant you a good morning)
* "How fares ye?" (How are you?)
* "Ha!" (A simple exclamation of greeting)
* "Good day" (Similar to modern English)
Other options:
* "Greetings"
* "Hail!" (A more formal greeting)
* "How now?" (A more casual greeting)
It's important to note that Middle English varied considerably over time and place, so the specific words and phrases used could differ depending on the specific context.