Need your advice ...
 

I need your advice in terms of buying a right VPS deal, so two hosts are in my mind: centohost.com and libertyvps.net, so what should I do?

I think you can ask them for some kind of test files in order to find out how different they are. Also I think that would be good idea to have more companies compared.
I would recommend you to include into your list hostry.com.

You can trust Libertyvps.net is professional web hosting provider. Everything works fine.
Customer service has always been fast and eager to resolve any question.

For service and support I give centohost.com a 10/10 and I highly recommend them. It should also be noted that I started out on a custom package after talking with sales and eventually worked my way up to one of their normal plans so if you need a custom plan talk to them as they will probably be able to work with you.

Pretty good SSDVPS hosting solutions you can order at hostnamaste.com - they are good, real good.
It has an amazing reputation for providing secured hosting service at very competitive price along with superb customer service.