It depends what you want. Timeshift is easier to use but it basically only serves one purpose. It takes snapshots of @ and optionally @home for system recovery. It does nothing else.
snapper is more flexible in several ways:
- It can take snapshots of any btrfs subvolume
- It creates read-only snapshots so they can be easily replicated to other drives or remote devices
- Snapper allows you to name your subvolumes however you like
- Snapper supports both flat and nested subvolume layouts
- Snapper doesn’t require the root of the BTRFS partition to be mounted
If you don’t care about any of those things, than you can stick with timeshift as it is easier to use and configure.