VPS plans from legionbox.com and hostsailor.com are provided on sweet terms and I have to select the best one for hosting a forum, so what should I do?

I host 5 wordpress blogs at Hostnamaste.com openvz vps and must say that I am happy with uptime, speed and their tech support is always online and ready to help. Speed is faster than I've had with my previous host! Customer support is responsive and helpful - work 24/7!

I vote for hostsailor.com.
They have been good going. Signing-up is easy with them. They are VERY reliable and whenever you have  a problem - they solve it. Pricing is good to say the least.

To choose hosting, you must first understand why you need it, for what tasks, what will be the approximate load, and so on.
Just a request in the style of "which of these two is better" is not correct, in my opinion.

But since such a question has arisen, then first of all pay attention to the work of the support service, since this is the most important thing. After all, no one thinks about possible problems while everything is working well, and when, through someone else's fault, your site (for example) stops working, then you will run to the first ones, to support. And they will either be able to help instantly, or they will read your ticket in a couple of days, since they, you see, have the weekend.

You're considering LegionBox and HostSailor for your forum hosting needs? Those are bottom-tier providers that cater to newbies and hobbyists. If you're serious about hosting a forum, you need a provider that can offer robust performance, top-notch security, and reliable uptime.
I'd recommend looking into more established players in the market, such as DigitalOcean, Linode, or OVH. Don't waste your time with these second-rate providers – your forum deserves better.

If you are still in search of good vps, can highly recommend Neironvps.com solutions.
NVMeVPS4 at $14.95/mo - CPU 2хE5-2680, RAM 4GB, SSD 30GB, Bandwidth 4TB per Month, Locations USA, Los Angeles, Germany, Switzerland.