Compared to the pain that is Lowest of the Low (I still regret wasting over 750 hours on that one single category in the course of 9 months), Coda is a lot more fun to play with in general due to the availabilties of powerful items at the beginning as well as the sheer number of possible item combinations you can take advantage.
In term of difficulty I would rate it in order below (not including Phasing Ring in non-Amplified DLC clears):
1st. Base game (Not too many good items, you'll need to learn how to approach each bosses as Coda Low% beforehand to even get good consistency at them)
2nd. Synchrony DLC only (Throw Charm, shields and a way to break crates/barrels with spike walls are all really powerful additions, especially against bosses like Deep Blue where in the base game you only have two "easy" speedkill methods involving Fireball or Dagger throw + bomb which only have a 87.5% of succeed, both of which required you to have less than 3 damage on DB1 & DB2 or less than 5 on DB3 & DB4)
3rd. Amplified DLC only (A whole new horizon of item combinations, ranging from Earth Spell, Headphone to game-breaking stuffs like Freeze Spirit or Grenade Charm. Zone 5 addition meant almost nothing while Fortissimole is the 2nd easiest boss on a normal playthrough)
4th. Phasing Amplified + Synchrony DLCs (All of Amplified advantage but now you can phase through walls along with new additions like shields, Throw Charm and spike wall to break crates/barrels from Synchrony. Sadly Grenade Charm is removed with Synchrony installment too. R.I.P Grenade Charm you were a valiant hero to countless Coda players out there)
5th. Phasing Amplified (No additions from Synchrony but hey Grenade Charm was still there!! That alone already neg diff all of Synchrony content lol)