I think the humans are meh in general,
The only one I actively used out of all 3 games was Miranda, and only because she had Overload and Incinerate, strong abilities that covered barriers, shields, and armor all at once. (And then that role was replaced by EDI in 3)
Choosing your squadmates is really just a matter of complementing your abilities. Kaidan favors synergy with biotic powers with his Reave setup (and Warp? I think?), while Ashley provides backup with tech powers and her inferno grenade (which is basically a free mass incinerate power that sets up for tech explosions).
Ashley's Marksman ability allows her to turn comparatively shitty weapons like the Revenant into a killing death machine, especially against high-barrier/armor enemies (depending on which ammo powers you have available)
At the end of the day, though, imo you can have better backup with the non-human companions in setting up biotic explosions and creating diversions. Garrus has always been a better all-round choice due to his Armor-Piercing Ammo and Overload. Concussion Shot is a fantastic disabler and a strong barrier-stripping ability.
Proximity Mine (which is possibly my all-time favorite skill in the ME series) provides a
universal 25% damage increase to any targets in (up to 3m) range. You name it - tech/biotic skills, explosions, weapon damage, a flat 25% increase is amazing, especially on Insanity. Carry it on your Shepard as well, and a Garrus-Shepard combo increases the damage buff to over 50%. It generates tech explosions, can't be dodged by enemies, staggers almost everything (interrupts Brutes and Atlases) except perhaps Banshees (but fuck those things srsly).
Also, it detonates and damages enemies who are behind cover. It
detonates through cover. I'm gushing here but seriously, proxy mine is an amazing go-to.
Liara provides Singularity which creates a static point at which to detonate a biotic explosion using just about any other biotic skill (Shockwave being a very effective method since you just have to point it in a direction but it's limited by range), Warp and Stasis. I don't actually use Stasis a lot either as an Infiltrator or a Soldier, but Warp is a good armor/barrier skill to use. But (as Lex might also say) she's a glass cannon and her weapon choices are kinda shitty. Squad Warp Ammo if you must.
Tali's also great for diversion but she's mostly geared towards tech-oriented Shepards and her misdirection skills like Combat Drone and Sabotage are decent but situational and very easily substituted for EDI's Decoy, which is a better general go-to and explodes fgj.
Also, pistols/shotguns is still pretty meh as far as weapons support goes. And speaking of EDI, she's basically Miranda 2.0 plus Decoy. Almost like a tech-support version of Liara with pistol/SMG function but better survivability using Defense Matrix.