As said, Havocs are the choice if you want a special weapon squad, not Chosen. A lot of people just don't know they work that way though, assuming they're just Devestators with spikes. Even Marking the Havocs comes out to Chosen prices for a minimum squad.
Chosen are an Assault squad, which is why they're a bad choice. Expensive weapons without a discount, and they're only suited to escorting a Power Armor HQ so they can still Sweeping Advance. And if you're taking a Power Armor HQ, you're already so far into the non-competitive scale that you may as well just take what you like. For instance, I take a unit of eight with Power Weapons on four and on the Champion, Mark of Slannesh and VotLW escorting Huron and a Sorceror, all of them in a Land Raider. It's a stupid unit, but I play fluffy Red Corsairs so include it for that reason. They murder about anything they meet and I use them as a bully unit, beating on smaller things while Terminators or Bikes or whatever else I have go for meatier targets. But Chosen are still only Veterans. They still die way too easily to more specialized units.