Both are acceptable although if you talk about general habits you would probably use present simple ‘I meet my friend every week for coffee’. Using with is not incorrect it is just more difficult to say.

I donʼt know

Hi, if you meet a friend it could be more of a coincidence, whereas if you meet with a friend It transmits more the idea that you have arranged It previously. Another way you can express the second meaning, is by using 'meet up with a friend'. I hope this helps 😉🤗

Usually using meet on its own refers to having an encounter with somebody while in combination with with it implies that this encounter is pre planed in some form. For example: I met my wife in a bar for the first time. Versus I met with my future wife in a bar for the first time. The first sentence implies that this was accidental whereas the other implies that you met with somebody in a pre arranged way. However this is more a rule of thumb thing... as there are examples in which the “with” is also dropped. Look here. https://www.learnersdictionary.com/qa/meet-and-meet-with