Title says all,mine’s glock because its your first firearm,accurate,semi auto,and… The shooting sound is more badass than MP5.
SPAS-12.
The Gluon Gun. Of course there hasn’t been a huge chance to ‘play’ with it yet, but the fact that it MELTS enemies now is just amazing.
From the top of my head… the TAU, definitely the TAU.
Listening to the ‘gun’ charging up is just too awesome, with a decent pair of headphones…
Gotta love it! 
Other than that, the Tripmines are one of my favourites, as well.
I love the Glock. Something about it feels so satisfying to kill something with it. Every headcrab death (that’s not by crowbar, anyway) feels so awesome.
I do love how a quick blast will make houndeyes explode.
I actually do quite like the hivehand. I used it far more in this game than in the original. I use it especially if I think there may be enemies in a room ahead. So I’ll blast a few bees into the room to scout things out and see if there’s anything bad there.
Magnum:
You can always rely on it.
On medium difficulty everything falls down with a headshot.
On hard you need 2 shots even against a Vort,but it’s useful anyway…
Crossbow
It’s really OP, if you shoot without the scope:
in Lambda Complex I killed an Assassin with it.
Probably tau, because I dont feel like colt is as reliable as it was in original HL. Tau instead offers more interesting gunplay, as I have to figure out and be precise with timing when charging it up against different kinds of enemies. I guess if it is about weapon which relies on aiming abilities, then Id rather play counter-strike, as my standards for aiming have increased by that decade I haven`t played hl.
Colt, what else?
Gluon Gun, it is amazing in this game, not only is devastatingly powerful but feels devastatingly powerful as well.
Tau Cannon for the same reason as Gluon Gun.
The crossbow, specially against the Black Ops Assassin to put my TF2’s Sniper skills to the test.
Hivehand is the coolest.
Magnum. My favorite weapon in all of the Half-Life games, and that didn’t change in Black Mesa 
The Crowbar.
Anyone else thinks Crossbow might be a bit overpowered ? The first time i used it to kill the Ichy I was surprised I needed only 2 shots. Well, Gluon and Egon are the most badass ones but I also like the Glock (especially with the new animations), so hard to choose… I think I’d go for the Tau…
And what happened to that cute “choo-choo-train” idle animation of the snarks ? The new one is kinda lame…
Hivehand can be used to skip most of the combat & even break scripted sequences once you get it. The glock & shotgun are the only good weapons up until than.
When wielding a trusty crowbar IRL, I actually feel like I am holding some sort of power as opposed to when I’m holding a gun I just feel stupid.
Magnum is my “Ol’ reliable,” whenever I am unsure about an area I whip it out. It is a great all-purpose gun. I also actually like the MP5, it is a great gun once you get used to using it. Tau is also pretty awesome, it has great accuracy and can be mighty powerful with a charge.
As far as the funnest gun though, the Gluon gun has no competition. Holy shit, the first time I used that gun it was like christmas morning. Explody enemies are so much fun.
I’m too used to the magnum being really accurate, so the magnum in black mesa just felt like getting a shotgun early. Using the sights on the thing boosts the accuracy, but takes too long & the model wasn’t aligned properly enough to use it at a distance.
The MP5 was only useful until I found out that the soldiers have significantly better accuracy with it, making it easier to use the Glock at a distance. Once I realized that I never touched the MP5 unless I wanted to shoot grenades. The impact grenades, while effective, were an odd combination of flying fast & falling fast, which made them seem really heavy.
satchel charge, feels more damaging than the original that and feeding it to barnicles is fun.