I've been using Namecheap for personal domains for around 10 years now. Since a few years back, privacy guard is included in the domain price (at least for .com domains) so your name, address, ... won't appear directly on whois queries.
As it's just one domain, (longterm) pricewise I don't think there'll be a big difference with any of them. 1 or 2 € per year, maybe. It'll be more important to check longterm price of the domain (.com / .io / ...), as you'll probably find some offer for the first year.
FWIW, namecheap publishes a recurrent offer around 10th October (apart from some random offers every once in a while) If you go with them, you can register for one year and renew the domain for a longer period when you find an offer.