KnownHost is one of my fully managed services, and I think this is the reason why I have not had any issues with them the last 18 months. Read more in my review.
KnownHost is a US based company with data centers in Texas, California and New Jersey. They are using Virtuozzo on their servers, and offer fully managed plans with both Plesk and Cpanel.
Their plans goes from 512 MB of RAM to 5 GB of RAM. With a price of $25 - $90/mo.
I'm using their SSD2 plan with 2 GB of RAM, 30 GB of SSD disk space and 3.000 GB of BW. I'm using Plesk 11 as control panel. The price for this plan is $50/mo and for a fully managed server with Plesk/Cpanel this is a good price.
KnownHost is known for their good service, and I have only positive experience with KnownHost so far. I have used their support once on 18 months, it was because I wanted to update PHP from 5.3 to 5.4. They responded in person within 3 minutes after I opened the ticket, an within 8 minutes the issue was solved. But three minute response time is really good.
The last 18 months, my VPS plan has been upgraded for free several times. I have gone from normal RAID 10 disks to SSD disk. My RAM has been upgraded from 960 MB to 2 GB. My BW has gone from 2.5 TB to 3 TB. And the CPU has been upgraded from Xeon(R) CPU E5645 to Xeon(R) E5-2630.
My monitoring services tells me that I have a 99.994% uptime the last 12 months with 1 minute monitors.
It just works. Almost no downtime (32 min last 12 months), no issues, no need for support. (just me asking for updating PHP) What a perfect host. If you need a fully managed host with Cpanel/Plesk in the US, take a look at KnownHost.com, and I'm sure you will be happy.