If you want the cheapest, go with Cloudfare. They guarantee to ask for the wholesale price, which is the price the registrar pays to the top level domain owner, so you can’t go lower without footing the bill.
What most of registrars do is foot the difference for the first year, so you get a domain for super cheap, then add 50%+ cut on top, so you pay i.e 5$ for the first year for a TLD that has wholesale cost of 10$, while they loose 5$ on that sale, and then you pay 25$ for the second, so they now gain 15$ on holding your domain hostage.
Cloudfare guarantees that they will sell you that domain for 10$, and only raise it when the TLD owner raises the price.
I’m not aware of any other registrar that guarantees wholesale prices.
If you want to get the best deal, buy your first yeae with the scammy registrar, i.e get the 5$ sale on Namecheap, and before the year is up transfer it to Cloudfare so you don’t pay extra for the second year and can continue with the wholesale price.
Issue is you are locked into the cloudflare system that is gradually enshittifying. Apparently NS changes are blocked, so you are stuck with them. This is not the case for other registrars.
Also for .com they are below wholesale, so they are banking on that enshittification.