What makes a Thunderbolt 3 enclosure good?

Hi howdy!
I'm in the market for a Thunderbolt 3 enclosure for my home computer. I've been looking all over Amazon and there's a lot of options at all sorts of different price points. But to be honest they all look/sound the same. So in y'all's opinion:
What makes a TB3 enclosure good?
What makes a TB3 enclosure bad?
What sort of specs should I be paying attention to?

Specific recommendations welcome!
If this matters, I'm getting this thing to get a bunch of audio, video, and photo files off my machine's main SSD, so I have more space for games.