based on your comments i suggest genesis and not just because i LOVE genesis but because it is:
1) easy to use
2) you can find cheap people to do the difficult stuff for you ( elance dot com )
3) many small alterations can be found on fiverr dot com
4) they have a great support forum
5) most templates are responsive but all will be soon
6) stick with just one template and you can create hundreds of different looking sites ( i know as i do)
then once you have some knowledge, branch out, i'd say the next step is woothemes, after that i'd say woocommerce, if you get that far you won't be doing any programming you will be just employing others to do it for you.
the benefit i find in sticking with 1 platform is when you employ people you know what they are doing and you know if they are doing it wrong or ripping you off. Also there is no reason why a website design for a dubbodentist can be then duplicated and used for a plumber in perth and that is where you save money on dev costs.
pay $x for the first one and then pay $x - $200 on the next, but invoice the same.
NEVER alter the genesis files !!!!!!!!!!!!!!!!!!!!!!!!!!!! only the child theme.
tim