I experienced lub's and it lags a bit, when I used Kalphiter's it was rarely any lag.
Lub's hosting is organized and nicely put together, but that isn't that makes a great hosting service.
Kalphiter's is easy to use, and that is all I care about, having a nice server without lag.
Although Kalphiter's prices are a little high.
also RTB doesn't have a very high variety of chooses from prices and times of having the service.
Both of them are good.