I have been a Heart Internet reseller for a number of years. the availability of software packages which can be used is excellent (Joomla, WordPress, Drupal to name but a few.)
The simplicity of the reseller control centre is great.
I only realised how good Heart are when I had experience of another provider recently who where significantly more expensive and the functionality was limited.
However it's the excellent support both in terms of speed of response and knowledge of respondents which I am very grateful for - especially when you are responding to a client's request.
Finally the price I pay is very good and has remained frozen for several years!