You don't have to choose between Tor or your VPN, use Tor over VPN to maximize your privacy.
A transaction is very small. So sending transactions over Tor is fine. (Downloading the entire blockchain is completely different matter, see below.)
Transactions over Tor are good for Bitcoin's fungibility.
Bonus: run your own full node, configure it to mainly use ...
First of all, anonimity and privacy are two different things. Bitcoin is designed to be pseudonimous - which is close to anonimity, but instead of being completely anonimous, you're linked to your bitcoin address, or pseudonym.
You cannot make a private transaction on the Bitcoin network, but you can try to be as anonymous as possible.
It is possible to run ...