I understand the importance of reliable and long-term VPS hosting with excellent customer support, I've been searching for a long time myself. Based on my experience, hostpro.com can fully meet your needs.
I can't answer specifically about Libertyvps.net, but their prices will be higher than hostpro.com
Regarding the server resources you mentioned, you can consider the
"NVMe VPS-1" tariff plan for $12 (100 GB NVMe, 4 RAM, 2 CPU, Unlimited bandwidth).
Regarding the operating system - if you do not care what version of PHP will be available (usually the problem is to find an operating system that supports lower versions of PHP), I can recommend Ubuntu 20.04 from free, from paid - cloudlinux 8
From control panels - from free BranyCP, from paid DirectAdmin
Hostpro.com has excellent technical support, which is available around the clock every day, both in chat mode and in a ticket. I get an approximate response in 10-20 minutes. In chat, 1-2 minutes.
You can contact them directly for advice and selection of a tariff plan)