Hi Karthik,
If you are already on ISA5.0 then It is advisable to go for ISA 7.0 as framework and look & feel is not going to change. I have done it for our client and it is easy as well.
I don't see any point to go for WECM & Hybris, but it is a fresh implementation then definitely these two options can be considered.
Thanks,
Hamendra