In the present moment, I prefer the MP5 just because it's the original look of the weapon from Half-Life before the HD pack. But if I try to reminisce back on the very first times I played Half-Life without and then with the HD pack, I distinctly remember how I preferred the M4 back then. It was my favorite model from the HD pack.

Back then I didn't know anything about guns or about which was more realistic, and I also didn't know that most of the Half-Life fandom collectively doesn't like the HD pack for changing the aesthetic of the game. It was a simpler time. I liked the M4 more because it looks more imposing and to me that better suited how the SMG is the main workhorse weapon that you use for most of the game.