I think the tutorials and documentation are a lot better for UE4, honestly. There may be a lot of material for Unity, but much of it is outdated, and I find it hard to follow video tutorials in Unity compared to UE4’s editor - it has too many panes and panels and tiny buttons and gizmos and stuff plastered all over, it’s way too hard to learn any real workflow amid that, much less interpret someone else’s layout during a tutorial and figure out where those options are on your own (probably different) layout.
The thing that got me was having to rely on multitudes of different asset store packs and things, and trying to integrate them all together, plus with whatever third party networking solution you decide on (since the base networking is meh, and would require integration into any packs anyway). As others have mentioned, you frequently come up against the issue of working on engine features rather than gameplay.
The source control situation with UE4 is vastly superior to Unity - no goofy source control server that costs $500/seat, and the integration is fast and seamless (Perforce). Haven’t tried Git etc but I magine it’s similar. Source control for Unity is annoying as hell (doesn’t get you until you have a bigger project and multiple developers, though).
In general though, I find the tools/workflow, documentation, and overall results to be quite a bit more pleasing with UE4. Progress on actual gameplay features rather than integrating engine-level middleware is a lot easier to achieve in a reasonable amount of time.