Namesilo is the cheapest longterm for domain names, and they don't try to upsell all the time.

Support system, they very fast, kind, and detailed, really help to solve my problem

Honestly, I really love their price for .com domains: $8.99 per year. I like their easy-to-use interface that allows you to manage all of the domains in one place. I like how good they are about features that other places would normally charge you money to have. I like how they have a live chat and that you can actually push your domains from one NameSilo account to another. I like how if you actually don't need the domain you registered/purchased with NameSilo you can sell it easily from your account or just drop it altogether without having to sell it. Transferring a domain to NameSilo is also super easy and I feel like my domains are really secure with NameSilo as the registrar. A place I really trust: LLC University, recommended NameSilo to me as what they use for their domains, and so I like how I'm using the same place as the 100% and utterly trustworthy LLC University. ;)