NameCheap has a great design also their support is on high level.
NameCheap also offer many promotions and have fair prices for their domains.
I hope you will go with NameCheap because from my side they are best option.
NameSilo works better as a reseller, as they'll let you brand the emails that come from them related to domain transfers and renewals, as well as being able to add branding and a link in the WHOIS records that they serve up on behalf of your customers.
Namecheap's prices are good compared to most, and their support is friendly and most often fast and correct in their answers. However a lot of features don't work, wasted lots of time having to remove 100's of WHOIS protections by hand.
I use both of them, but I believe that Namecheap is way better than Namesilo. But, Namesilo's prices are much better than NameCheap..But anyways I believe and I'm sure that Namecheap is way better than NS, Check it out and you won't face any problems.
I use namecheap for both domain registration and hosting. I can attest to their awesomeness. Nice easy interface and great customer support that listen and attend to your request with passion. Oh, lest I forget their cost is cheap as well.
I have never tried Namesilo even though I have read good reviews about this domain registrar. I am a happy namecheap customer. I have almost 100 domains with namecheap, most of which I registered during the promotion. Since I am very satisfied with namecheap, I never considered joining another registrar of hosting company.
When I first started buying domain names I used GoDaddy, but now I use Namecheap both for purchasing & managing my domains, and also for their hosting. I've never had any downtime (that I've noticed) and the pricing suits me. I find it easier to keep everything in the one place.
They often have some good coupon codes for cheaper domains and hosting which is an added bonus for me!