Ive switched to managing own VPS about year ago. It's not hard but it takes some learning. Its actualy quite fun and it will make you better developer knowing webservers.
I have had experience with lot of the forementioned providers
ovh.com - digitalocean.com - linode.com - vultr.com
All of them are more than capable and high quality. I switched from digital ocean because of pricing. Ovh is usualy the cheapest but their admin interface is not so polished (which doesnt matter because you use it very little). Linode now has 5usd plan and they are precieved as higher end although even from tests all of them are on par. Vultr started to be pretty agressive with its pricing (2.5usd for the lowest plan) its now priced maybe even lower than OVH. Also vultr only one you can pay with bitcoin.
Even the lowest plans can get you suprisingly far - we run multiple sites on the lowest tier with no sweat. I mean it depends on how much users you have but most of the people will be using kirby for sites with smaller audience.
In the end the bottleneck is usually harddisk space - especialy when your client uploads his 1.5gb - 20 slide presentation. Also memory can be bottleneck but even 512MB is quite enough if you run just sites there.
If i was picking now i would probably go for VULTR or Linode or OVH. OVH tends to run promotions when they have new servers - i snatched 1gb ram vps for like 20usd / year this way.