Dungeons & Dragons 5e was good at telling you what your most important ability scores should be for each class. The D&D 2024 Player's Handbook, on the other hand, is good at telling you what your dump stat should be.
You have six ability scores in D&D: Strength, Dexterity, Constitution, Intelligence, Wisdom, and Charisma. The only weird one in the group is Constitution, simply because it conjures up images of Founding Fathers and John Hancocks more than being the definition of endurance and vitality. Also, knowing the difference between Wisdom and Intelligence has been a puzzle for millennia. Regardless, this is how it's always been. Some would argue that ability scores are less important than the modifiers they bring. I would argue against that and, with the 2024 PHB's inclusion of personality traits to go along with your ability scores, D&D reaffirms the importance of ability scores over modifiers.
There are a few different ways to gin up your Strength, Dexterity, Constitution, Intelligence, Wisdom, and Charisma. My favorite has always been Random Generation with the dice: Roll four six-sided dice, drop the lowest, and add up the remaining values. Say you roll a 5, 4, 1, and 2. You drop the lowest: 1. Your add up the rest: 11. After you've done that six times, once for each ability, then you go about assigning those scores to your Str, Dex, Con, Int, Wis, Cha.
Another way to generate ability scores is through Point Buy. I've never appreciated doing the math. You're given 27 points to spend. The cost of each score is located on an Ability Score Point Costs table. For example, a score of 8 costs you 0 points, while a score of 15 costs you 9 points. You can min/max your way to an interesting build. Such as ending up with three 8's and three 15's. No matter what you assign those scores to, you'll end up as some kind of idiot-savant. Boringly, you can spend all 27 points coming up with the exact same spread of scores used in:
Standard Array. With this method, you're given a 15, 14, 13, 12, 10, and 8. You assign them where you will. That's it. Those scores add up to 72, which isn't bad. (It happens to be exactly how much my scores added up to using the dice-rolling method.)
A new table added to the 2024 PHB is the Standard Array by Class. The table lists all the classes: Barbarian, Bard, Cleric, Druid, Fighter, Monk, Paladin, Ranger, Rogue, Sorcerer, Warlock, and Wizard. Then it has columns for Str, Dex, Con, Int, Wis, and Cha. Populating this table is the most sensible place to assign each of those Standard Array scores: the 15, 14, 13, 12, 10, and 8.
The 5e PHB was good at telling you the most important ability for your class, as well as the second-most important. A Barbarian would want their highest score on Str, and their second-highest on Con. While a Wizard would want their highest score on Int, and second-highest on Wis.
But where do you put that pesky 8? That's a below average score. Whatever you put it on is getting a -1 modifier to your dice rolls. The existence of that 8 makes it important to identify your class's dump stat—a stat that is the least important to your class.
Well, with this new table in the 2024 PHB, your dump stat is instantly identifiable. For a Barbarian, your dump stat is Charisma. Put that uncharismatic 8 on that bad boy so that your Barbarian's Strength and Constitution can shine. For a Wizard, your dump stat is Strength. Let the meathead Barbarian figure out how to hit things really hard. You've got books to read and spells to sling.
Feel free to go against the game designers' wisdom, however. Making a brainy Barbarian or one of those idiot-savant Wizards would make for some wonderful roleplaying moments. But if you're new to making characters in D&D, check out that Standard Array by Class table. That way you'll know what your dump stat should be no matter what you're playing.
On the Dump Stat scorecard, that's four for Strength, one for Dexterity, four for Intelligence, and two for Charisma. So there you have it. The most dump-statted stats are Strength and Intelligence.
This inversely tells you which ability scores are never dump stats: Constitution and Wisdom. Because everybody needs hit points (from Con), especially if you don't want to become "Bloodied" yourself. And everybody needs Perception (from Wis), especially if you want to catch all the little text-and-artwork Easter eggs throughout the book, like the Alignment Chart Meme they just added.
Do what you will with this information. As for me, I need to rearrange my Bard's dump stat to be Strength instead of Intelligence as I naively made it. I'm a Bard! An entertainer. Who needs Strength when your job is to do an intimidating, shirtless New Zealander Haka Dance at the start of every battle? On second thought, with my shirt off and all, maybe I'd like that Str back, please.