When 5E came out we used the default array for the PCs. After a year or so we started using 4d6 drop the lowest. It tends to result in higher scores than the default array. Put simply I think 5E function better and it opens up more options with higher ability scores.
Put simply it seems to fix certain classes if you roll high and it makes things like TWF more viable and it also makes medium armor suck less. It also makes things like the hypothetical Mountain Dwarf wizard or Sorcerer more viable.
All of the gish classes also look a lot better if you roll higher ability scores. If you roll crap the Moon Druid is a great class along with the Morph from EN5ider. A main problem of all the gish classes in the PHB with the exception of the Paladin is multiple ability dependency (MAD). Put simply to be effective you need a good physical score, spellcasting stat, decent con, and dex as well if you are using medium armor. Put simply you kind of want 4 stats 14 or higher or a 14 dex with medium armor or 15 strength in heavy armor. Valor Bards are a prime example as they want a decent attack stat, charisma, dex and con. Most of the gish also are not proficient in con saves.
The dex based melee classes and TWF also tend to get over shadowed due to certain feats (unless you are having a featless game then dex is super stat). This is because you want to get a 20 dex ASAP so you can get your 17 or 19 AC (AC 18-20 strength based generally). With point buy you can get 20 dex by level 6 or 8. A 20 strength is nice for a strength based fighter but 18 strength+ feat is a great option as your AC is not keyed to your strength score.
Other options that tend to be a bit meh are things like Bladedancers in SCAG. Under point buy they are not actually that good at erm blade dancing and you are better off usgin it to enhance your AC, movement and concentration rolls than attempt to be a bad fighter. Our Bladedancer rolls 3 scores over 16 and with racial modifiers + resilient(con) feat she has 3 18's at level 4 (con, int, dex). She plays a very aggressive wizard suffice to say in regards to melee and uses flaming sphere+ melee attacks (1d8+4+2d6+2d6 damage lvl 4).
So basically my players are mnoving away from the usual feats as they tend to have higher ability scores and prefer being awesome with new options (monks, gish, etc) over abusing the usual suspects (GWM, SS, CE, PAM) which they did earlier in 5E's run. We have Rogues defaulting to daggers as a weapon, sword and board fighters using short swords, assassins dual wielding.
