While the Champion subclass itself hasn't changed much, the changes to the Fighter class itself makes Champion crit builds much more interesting. Here's a build I've been playing for a few sessions. It's not pure PHB 2024 as it uses Elven Accuracy from XGtE, but it's still considered non-Legacy as per 5e 2024 rules.
As a race, you want Elf, Half-Elf, or Eladrin, so you can access the Elven Accuracy Feat. And you also want Crossbow Expert, and Piercer. You'll take the Archery Fighting Style, and use 2 Hand Crossbows, which you'll pick among you weapon masteries. Thanks to Vex, the only time you'll not roll with advantage is on your very first hit, for which you can use your Heroic Inspiration given by Heroic Warrior at level 10, but even that won't matter at level 13 as you'll be given advantage on the next attack even if you miss. As you level up, your crit chances will get super high.
At level 4, Elven Accuracy and Improved Critical will give you a crit chance of about 27% on each attack with advantage. When you get Piercer, you'll add an extra d6 to the damage on each of those (also you'll get to reroll some 1s). When you get Crossbow Expert, you'll be able to dual wield HCB for an extra attack with your BA, and use your HCB at close range. At level 15, your chances of crit will jump to a whopping 41% with Superior Critical. Also at that level, you'll make 4 attacks per turn, unless you use your BA for something else. And that's not even taking Action Surge into account.
But there's even better. You can take a dip into Ranger (make sure you prepare for it as you need 13 WIS) and get 4 Hunter's Mark per LR (more than enough, even at level 1). On average, Hunter's Mark will outdamage dual wielding after only 2 attacks, so it's totally worth it. You could also go melee, take a rapier (which also has Vex) and a shield, and take Dueling instead of Archery. Lots of possible variations, as long as you have the basic components: Elven Accuracy + Improved Critical + Vex Weapon Mastery + Piercer. And Piercer isn't really that necessary, but because you'll crit so much, the extra damage is significant. Another very fun thing you can do is take the Skulker feat and cast Fog Cloud on your enemies. Your teammates might not find this very fun for themselves, though.
While the Champion subclass itself hasn't changed much, the changes to the Fighter class itself makes Champion crit builds much more interesting.
Here's a build I've been playing for a few sessions. It's not pure PHB 2024 as it uses Elven Accuracy from XGtE, but it's still considered non-Legacy as per 5e 2024 rules.
As a race, you want Elf, Half-Elf, or Eladrin, so you can access the Elven Accuracy Feat. And you also want Crossbow Expert, and Piercer.
You'll take the Archery Fighting Style, and use 2 Hand Crossbows, which you'll pick among you weapon masteries.
Thanks to Vex, the only time you'll not roll with advantage is on your very first hit, for which you can use your Heroic Inspiration given by Heroic Warrior at level 10, but even that won't matter at level 13 as you'll be given advantage on the next attack even if you miss.
As you level up, your crit chances will get super high.
At level 4, Elven Accuracy and Improved Critical will give you a crit chance of about 27% on each attack with advantage.
When you get Piercer, you'll add an extra d6 to the damage on each of those (also you'll get to reroll some 1s).
When you get Crossbow Expert, you'll be able to dual wield HCB for an extra attack with your BA, and use your HCB at close range.
At level 15, your chances of crit will jump to a whopping 41% with Superior Critical.
Also at that level, you'll make 4 attacks per turn, unless you use your BA for something else.
And that's not even taking Action Surge into account.
But there's even better.
You can take a dip into Ranger (make sure you prepare for it as you need 13 WIS) and get 4 Hunter's Mark per LR (more than enough, even at level 1).
On average, Hunter's Mark will outdamage dual wielding after only 2 attacks, so it's totally worth it.
You could also go melee, take a rapier (which also has Vex) and a shield, and take Dueling instead of Archery.
Lots of possible variations, as long as you have the basic components: Elven Accuracy + Improved Critical + Vex Weapon Mastery + Piercer.
And Piercer isn't really that necessary, but because you'll crit so much, the extra damage is significant.
Another very fun thing you can do is take the Skulker feat and cast Fog Cloud on your enemies.
Your teammates might not find this very fun for themselves, though.