Do you use the paid tier of NS1? Upgrading to a paid plan in the $45/month range is way beyond my low-end budget, 50 RR’s is nowhere near enough for all my stuff, and I’m using 400k of the 500k limit for just one of my subdomains.
Don’t get me wrong, I love NS1 and use it myself for my most important things. I recently spent a few hours integrating Uptime Robot health checks into the NS1 platform, which shows how flexible their platform is. But moving to a paid plan? Nah.
Get a few cheap KVM’s with AntiDDoS and run a dns service on them.
https://clients.hostsailor.com/cart.php?a=add&pid=447
Sadly already OOS, was a 256MB KVM with v4 for 6$/y.
Also BF is over so, most likely you stuck with Free DNS providers such as Zilore.
Regarding dns.he.net, I think they still do that thing where their servers stop returning queries for your domain if they don’t detect your nameservers as being pointed to them(?)
Ref. comment by @Jarland in old thread/topic here.
Pricing? More pros/cons/features? 
Yeah, it means downtime to switch to them because there will inevitably be a stage where they don’t detect it yet someone else does, so their system queries HE and gets nothing in return. Not so bad if starting there, but rough if moving production to it.
I use HE as secondary with a hidden master and don’t recall this problem, but possible my memory is faulty.
I used the free DNSmanager.io by HostIO for a while, really nice product, I especially liked the templating. They just moved away from free to a price model that’s quite fair, but didn’t match my scenario (up to 10 domains €14.90/yr, €49 for 100, IIRC).
I have now moved some domains to FreeDNS by 1984hosting.com. It seems like a really nice service. UI not as polished as DNSmanager, but still quite nice. They’re free, but commercial support is $49/yr. Setting up DNSSEC was nice and automated. They also offer HTTP redirects. FreeDNS also had funny error messages, like “Poo poo characters in hostname” … 
I’ve also been testing dynu.com (also quite nice, a bit different UI, kinda focused on dynamic DNS). Free plan is 4 hostnames (sort of *.domain.tld, except subdomain). Paid plan is $9.99/yr for 50.
www.GeoScaling.com also seems nice, and has some handy import/cloning options (for https use secure.geoscaling.com, IPv6 only). This has some unique features, maybe I’ll switch to using these more. 
Very responsive and friendly support. Free, open for donations.
None of these offer ANAME / ALIAS / “flattened CNAME” for the main host (mydomain.tld), I think.
Maybe you ask, why not CloudFlare? Good question, and I don’t know, really. Kinda considering them for some CDN/proxying, free and good performance. Only argument against would be that they already own too much of the Internet? (Though they don’t seem to he bad guys, Google and others seem “worse”?) Also, I’ve always liked the smaller companies … 
I’m open to other cheap/lowend/free CDN/proxy suggestions.
(Am using Netlify, but free plan seems a bit slow in my tests.)
Hetzner offers free authoritative DNS even for non customers, but not anycast.
Vultr offers free DNS too, and it’s anycast but not very full featured (for example. no ALIAS).
Netlify offers unlimited NS1 for free, which should be great if you trust VC backed companies.
Rage4 is cheap, but they deleted my grandfathered account without notice, so I’d avoid them.
Other providers which I wouldn’t use but could be ok for others.
DNSPod is very big and free, if you don’t care about the owner (Tencent)
DNS4.PRO was associated with Prometeus a long time ago, but not anymore (I guess).
Many cloud providers offer free DNS, but most of them as an afterthought, so I’m not listing those.
And finally, secondary old-school services which have been around for two decades:
PUCK Free Secondary DNS - single NS in the US
Trifle NS2 - single NS in Ukraine since 1998
Twisted4Life - single NS in Malasia. abandoned, wouldn’t use it
Didn’t know Netlify DNS was free. Still some limitations (subdomains or something not supported IIRC).
Hetzner is nice, but geographically not spread very well yet. And not DNSSEC (or ANAME).
I thought Vultr was free only for active customers, if I’m wrong, good.
Any reason to not trust DNSPod/Tencent? (I don’t know them.) Looking at their website, kinda hard to tell the pricing model, looks like it’s free if you use them as registrar. They certainly don’t flash the words “Free DNS” too much … 
DNS4.Pro seems to be 5 domains free.
DNSimple is a nobrainer for $5/mth for 5 domains, and $0.50 for each added domain.
$7/yr max
from DNSimple pricing page :
Save $10 when billed yearly.
Still $50/yr for 5 doms… but quite decent specs, almost on par with CF.
Tencent is a very big Chinese conglomerate with a stack in a lot of Chinese and international IT companies. DNSPod is completely free, at least the international version.
I use ClouDNS for some of my stuff, it’s pretty cheap (unlimited queries are nice) and it has a workable API.
HOWEVER their anycast sucks (seems they have no idea what they’re doing) and I’d avoid using their CNAME flattening feature, it’s horribly broken. Trying to combine it with Bunny results in pretty much everyone getting routed to Amsterdam… but I guess that might be a result of the anycast being broken as well.
Yup, still getting the job done.
Does it work well? Is we believe dnsperf they don’t perform that well outside of EU/US: DNS Performance for Vultr DNS | DNSperf - given the many locations they have, if their anycast is setup to use all their locations I don’t see why performance isn’t better. It’s still decent and probably more than enough… I guess choosing them or not rather than CF (in DNS only mode) depends on CF being really evil or not
Nobody running their own authorative DNS server ?
Plenty of ultrafast and secure alternatives for BIND these days !
Yadifa 
(my personal pick)
NSD from same makers as Unbound 
Yeah! I’m running about three DNS Clusters now for myself and the Company 
All rocking PowerDNS, super nice to set up, and a lot of features. It supports quite a few backends, MySQL, SQLite3, bind zone files, etc…
I also offer DNS Hosting on those Clusters, one of them Anycasted with 14 Locations # self-promotion
