I personally prefer Nextcloud, but it probably depends on what your goals are. If you want to keep two folders on different devices synced with the same files in both places, Syncthing is probably the way to go.

I opted for Nextcloud because I prefer the option to store almost nothing locally, and I have the ability to set up access for other family members and friends with granular restrictions on what folders they have access to, and even give them a storage budget. But yes, that makes Nextcloud quite a bit heavier.