Shusui’s a really good sword with no disadvantages to it.
Enma’s a fun balance of the sword saying “master me or I will kill you.”
A fully mastered Enma that’s became a black blade (and one of the top Meito) is outright better than Shusui.
Funnily enough, if current Zoro was to swap the swords back he would be stronger assuming he could still use KoH. But Enma still has room to grow whereas Shusui doesn’t, so Enma long term is the better sword.
Putting it in video game terms.
Shusui- level 80 sword (cannot grow anymore), AP consistent 750, defence 890 (as a black blade)
Enma- level 75 sword (can grow to 99), AP 630 to 950, takes HP whenever you attack, defence 500 (not a black blade), unlocks KoH mode
Meanwhile Wado and Sandai are like
Waso- level 60 (can grow?), AP 500, defence 500, provides bonus to mastering Enma
Sandai- level 30 (can grow?), AP 550, defence 320, cursed but mastered
Or from another perspective as like a class change, Zoro using Shusui is a Knight, with Enma he’s a Dark Knight
Shusui is the safe option, Enma’s high risk and high reward.