Windscribe, hands-down. They're open-source and use Freemium pricing, so it's completely free if you use up to 10 GB per month (or 11 GB if you don't mind using a referral link - https://windscribe.com/yo/v40g2xlr)
Their speeds are faster than Proton, even at the free tiers, and also permit Netflix/streaming and tormenting/p2p, they frequently have big discounts and giveaways for pro plans, and some pro plans start at $1/mo. They're my absolute favorite VPN and I'm always shocked they're not more well known.