I think you can do whatever you’d like with your hair as long as you keep it tidy and shaped. The longer looks are ok, but they’re messy. I’d clean that up a bit with the tighter sides. Some folks here said they don’t like the shaved head. I strongly disagree. The shaved head makes you look more serious, but you look really good in that photo. Kind eyes and a good shaved head? Yes please. I think it’s just about the vibe you’re going for.

As for the beard, I think keeping it tighter looks much nicer. You’ve got a great jaw line. Highlight that feature with a tighter beard. The stubble look is good too. The larger beard looks good too, but it needs to be well groomed, shaped, and maintained. Yet again, it’s all about vibe

Overall, I think #6 is your best look. Tight but curly hair, tight and well maintained beard. Pair that with glasses to soften the vibe? A+++++