This is just my opinion, but let it be known that I do not use VPS. The reason that I recomend KnownHost, is for the simple fact that I think they are very reliable, and that their support is really great.
My facts behind my opinion are that my company manufacturers their servers. You may think that I am just trying to push you towards a company that I am close with, but really, I do not get anything out of this, so that is not my intentions. If it were I would just lie to you and tell you that I use them and they are the best. Also, I have other accounts, not to mention a larger one that also provides VPS hosting, but I would not feel as comfortable recommending them as I would KnownHost. Nothing against them, they are great companies as well, I just feel that KnownHost is better by far.
Now, as I was saying, the servers that they purchase are really high end configurations, and top brand components. They spare no expense when it comes to parts. Another thing is that we put each of our servers through rigorous testing, burn-in test and what not, but they take it even a step further. They root into the servers before we even send them out, and do their own 72hour tests on them. With this being so, you can conclude that their uptime must be high, if not perfect.
As far as their support goes, I deal closely with their top support guy and he is a guru at what he does. They have never once called in about an RMA issue, or ever required support from us.
As far as a reputable company, they are constantly expanding. They purchase a minimum of 3 servers a month and have even purchase 18 from us one month not too long ago. On average, they purchase around 5-6 servers per month, so they must be doing something right.
Now I hope that I did not bore you too much with this essay that I just wrote, but the choice is ultimately yours. I just wanted to put my 2 cents in.