I am using colocation services from XSServer / SkyLink and they are great. The prices are very good and they are always trying to find the best solution for you.
A problem occurs, maybe on Saturday evening? No matter, the friendly staff is always reachable and they always find quick and professional solutions for you.
What I really like is the way of communication, it's very personal. You can easily contact the owner(s) of this company and I personally do always have very nice and interesting talks with them when I am at the datacenter for my colocation services.

Also the other services XSServer is offering do have a great level of quality, no matter if dedicated servers, VPS or other services like domains.