Bitcoin Core is the reference implementation of the Bitcoin protocol. Running it means the software independently validates every block and transaction against the consensus rules instead of trusting a third-party service, which makes the wallet the most self-contained option for holding bitcoin.
The package includes a graphical interface, the bitcoin-cli tool, and a JSON-RPC interface that other desktop wallets and scripts can use as a backend. Pruned mode keeps disk usage to a few gigabytes, and wallet files are encrypted with a passphrase you set.
Windows 10/11 x64, 8 GB RAM, SSD with room for the blockchain