I also recommend Aldi-Talk. They have a variety of plans and offer in my opinion the best value if you want to keep monthly spending low. It’s prepaid, so no yearly subscription. Afaik the SIM itself is free. Only issue: setting up the account to automatically withdraw money is quite a hassle. But you can buy codes similar to paysafe cards (do they still exist?). Note: That was a few years ago, might have changed by now.