At 3rd-level Chromatic Orb (CO) averages 22.5 dmg vs. FB at 28. As
@FrogReaver says, you have to hit, so I'll go with the 65% standard.
For a 3rd-level CO, you have the following:
No hit: 35%
Single hit (no leap): 13.325%
Single hit (leap, second target missed): 18.0863%
Two hits (no leap): 6.8857%
Two hits (leap, third target missed): 9.3461%
Three hits: 17.357%
At 22.5 damage on a hit, your expected damage is 26.08779 total. For FB, with 35% save, each target has expected damage of 23.1, but FB and other AoE spells are assumed to target a minimum of 2 targets, making the damage 46.2 minimum expected.
Each target will take more damage with FB, and you can easily get more targets,
so unless you are SUPER worried about friendly fire, FB is still much better.
Compared to Chain Lightning (CL), CO at 6th-level is still a worse spell for damage. Total expected damage for CO is 61.6, while CL is 74.25 even if you just hit two targets--and odds are you will have more than two targets if you are going to use the spell. And with CL you don't have to worry about friendly fire.
The biggest issue is the attack roll, obviously. Now, as the OP states there are a lot of ways to buff attack rolls, and if you have targets with lower ACs, it becomes more viable.
Over all, the new CO is an "improvement" over the 2014 one... (hardly unexpected...), and can certainly have its uses, but in general I'll stick with FB and CL myself, however I can certainly see the appeal to others for a useful spell in close quarters or shorter range. Honestly, the more appealing aspect for CO IMO is you can choose different damage types, and aren't tied down to fire or lightning for FB and CL.
Finally, CO is a ranged attack, so you have to worry about disadvantage if you have a hostile creature within 5 feet of you (unless that changed in 2024?), with FB and CL you can be surrounded and it doesn't matter for the success of the spell.
DISCLAIMER: the bounce percentages I used in my calculations do not include the increased chances of bouncing when scoring critical hits. The improvement when adding it is negligible IMO.