For me it's a familiarity thing. I'd been using Sync for Reddit for close to a decade. It's my defacto standard for feature set in these types of apps. I've tried and continue to use the apps that came out first, but every single one of them has quirks that don't align with how I prefer to use the platform. Sync does.

Saying all the apps are literally the same makes me wonder what it is you're looking to get out of them/how you use them. Do you like to share images from posts with people outside of Lemmy? That's easier on some than others.

For example, on Summit I have to open the image in the internal browser then the external browser then copy the link/share from there. On Connect they have a 3 dot menu that has a share url option. On Sync it's a 3 dot then share option/copy URL to clipboard.

It's little nuances like that that make or break an app for me. At a certain level these are all just interfaces to interact with the Lemmy platform so they are going to be similar in many ways. But some apps can offer a better user experience than others. It really depends on what you want/how you use the platform.