It really depends on playstyle. Heavy Weapons are generally going to be guaranteed kills under most circumstances, so listing them is pointless. There's a reason why Heavy Ammo is so important in Crucible. But with primaries and secondaries, I'd say that you could moreso list categories than just weapons.
Handcannons are still really strong. The nerfs made them more manageable, but they're still some of the strongest guns in the Crucible. I'm going to go ahead and just group up the three exotic handcannons, but their usefulness comes down to your preference in playstyle.
After that, I'm going to put pulse rifles on the list in another full category, but not all of them. This is just around Red Death, Bad Juju, Stranger's Rifle, and maybe one or two more.
The Vex Mythoclast is in a realm of its own, so it gets its own step on my list. High damage output, fast rate of fire, and awesome in mid-range encounters. Unless your enemy has a Last Word, Red Death, or Hawkmoon and you both are on equal footing, you're probably going to win the exchange.
Shotguns in general are still very strong. Universal Remote and Invective are really useful. Two the Morgue, Swordbreaker, Fellwinter's Lie... There are a lot of really good shotguns that can help you in a close-range encounter.
Sniper Rifles. There are a lot of maps where these excel, especially in control situations. In many of the maps, you can snipe right down toward another control point. And some of the maps are open or wide enough where you can kill people as they rush you. Or attempt to. I've used No Land Beyond on a few of these maps (Venus and both Earth maps on Control are hilarious) and it does surprisingly well. Now I'm not going to put No Land Beyond in my list, but generally a good sniper shot is a one shot kill from across the map with little room for retaliation. It's a little more niche, but still very effective. Especially after Fusion Rifles were slightly nerfed. Patience and Time is very funny in a lot of these maps, too, as it's hard to lock down a good player using one as they wander around picking your team off of important objectives. Black Hammer, LDR 5001 (even better assuming the armor piercing still lets you kill through walls), Patience and Time, and even to a lesser extent Ice Breaker can be amazing given the right circumstances and the right map. And even when you're not shooting across the entire map to kill someone, there's something oddly rage inducing than walking into a room that has no radar activity only to be sniped from down the stairs. But being on the other side of that scope is very satisfying.