I'd say Shichibukai and crews are better than any Emperor crew , but since there are 4 Emperor crews , not sure .
The Shichibukai and crews are better for me because they are more diverse than any Emperor crew ( more themes )
They have animal themes ( well not all but : )
Mihawk - Hawk
Boa Hancock - Snake
Jinbe - Shark
Crocodile - too obvious
Law - Tiger i guess ( Torao )
Kuma - Bear
Moria - Gecko
Teach - Hippo i think ?
Doflamingo - Flamingo
Heck some of their territories when you combine them will be cool , and have different themes
Mihawk - Kuraigana , dark island
Moria - Thriller Bark , even darker , and it's more of a ship yea ....
Crocodile - Alabasta ( full of deserts )
Jinbe - Fishman Island , underwater island
The rest ( Karai Bari , Dressrosa , Amazon Lily ) aren't bad but not likeable enough for me
Of course Big Mom have diverse islands as well , but they all are still under Foods theme
Overall Shichibukai and crews are just better for me . also they have big scale attacks
( Mihawk's slashes , Kuma's Ursus Shock , Doflamingo's BirdCage , Crocodile's Sables , Shadow Asgard that can split TB especially if Moria in his prime will be stronger & cooler , Jinbe's Buraikan shook Wadatsumi )
Pica in Golem also is estimated to be far larger than post skip Emperor crew's biggest giant ( Pica is estimated to be 800m tall , San Juan Wolf is 180m )
well San Juan Wolf is EOS Chopper's opponent though
Also pre skip Oars ( 67 m , from Moria's crew , was bigger than pre skip Emperor's biggest giant ( Oars Jr. , 38 m )
i guess Emperor crews are better in some ways , but Shichibukai and crews are more likeable to me .