I've used all the service providers available and these opinions include my historical experience with them (I've used all providers for many years, my account with DO is since 2013). Most of my service uses were focused in those service provider's North America locations, Asia locations, and Oceania locations. Note I did do a short comparison between DigitalOcean and Vultr back in 2014 here: https://vpsboard.com/threads/digitalocean-vs-vultr-the-asian...
Most service providers here are fairly decent.
From my experience, OVH's KVM VPSes weren't worth the time, but their VMWare VMs were absolutely top notch.
Linode has had two major security events over the last few years, one of which was in early 2016 which included release of credit card information. However, they also offer paypal payments now and are fairly top notch in terms of performance. (They've taken approaches to fix their problems from 2016 with this blog post here: https://blog.linode.com/2016/02/19/security-investigation-re... ).
DigitalOcean is fairly reliable. Their Singapore location early on had regular packet loss events, but they've been shaping up pretty nicely over time.
Vultr has been a major problem for me. Vultr for a while (on their storage instances in Japan) had terrible I/O which took a solid two hours just to install Ubuntu 14.04. When contacted support, they stated they "stopped a noisy neighbor and to retry" but no real improvements were seen.
We had a service running on a VC2 that irregularly required a large amount of CPU power (higher than 0.5 load on a 1 CPU instance for a period of 1 hour a night). The same task was completed faster with VMs from DigitalOcean and Linode. But the biggest problem I've experienced is their network.
For the longest time their Japan location was single-homed and routing was funky. We'd regularly see any traffic going outside of Japan being routed back through their Los Angeles location, so adding 300+ ms latency for any of our users in Korea, China, and anywhere in South-East Asia. Today it's much better with 40 ms latency from their Japan location to our Korea client, and a solid 80 ms latency to our Singapore client.
A colleague of ours had very important clients who required 100% uptime (which Vultr agreed to) but over a period of a month had regular packet loss events or network loss (regularly 40 minutes per event and around one event every few days monitored via external monitoring systems such as uptimerobot, statuscake, and a GCP server running Icinga2). Didn't receive much help from Vultr's engineers nor could they find the issue. They ended up moving to Google Cloud Platform. They did end up getting SLA credit from them but no reason to have SLA credit when you're not on their platform anymore.
I regularly return to Vultr every few months to every year or so to see how it's going and they've come a long way with the services they're offering. I'd recommend them for a dev environment and testing over a period of an hour a day or so. However, I would caution with production systems. Your mileage may vary, but I'd suggest reviewing the quality of the product in addition to the price tag per resource.