Grayduff,
Following on from my earlier post I think what groupset you will end up will largely be determined by the size of your budget.
In the new bike budget range say up to 700 you will invariably find Tiagra / Sora stepping up to about 1k you will find 105 may be the odd ultegra above 1.5k and a lot higher invariably you are into Dura ace Di2 territory
It is a balancing act and certain manufacturers provide a certain spec and will concentrate on certain parts. For example you may have one bike offering 105 or ultegra and the rub is that you have a pretty shoddy set of stock wheels, others may set more store by wheels and the rub is the group set and so on and so on.
Evans cycles have a good range of bikes have a look at the bikes in various budget ranges and you will see some patterns emerging re bang for your buck.
Certainly best advice is get the best groupset for your budget, however if your current budget is X and this means you end up with Sora you can either put up with an "adequate" group set or wait until your budget gets larger and get the better group set.