Both SS and SRT have exceptional performance!!! Just one is better at straight line acceleration due to a larger displacement/higher output engine (SRT) and the other (SS) is better at carvin up the twisties due to a more advanced suspension/chassis. Both are excellent cars, and both can be vastly improved upon in both areas. Overall performance will be neck and neck on these cars once the aftermarket catches up with the SS which wont take long with huge vendors like Modern Performance and a few others joining in.
A lot of people say the SS looks better due to the fact that it is in coupe form, yet I think the SRT would e more practical w/ four doors.
From what I hear the SS will probably run at a higher price due to the nice interior, quiet steel, and other luxuries so performance/$ is better w/ the SRT-4 but overall value/$ is somewhat arguable yet I lean towards the SS.
So all in all considered, it really is completely up to you, its your decision to which one you like better that you should base your choice on.
Good luck with whatever path you take!