I am looking for ideas for best shopping cart that can be versatile and edited. Symfony based preferred however if you feel others would be better let me know.
Quick.Cart is free,
eCom Cart is best.
I don't know if you can manage to complete the entire payment process
(PayPal and similar services are integrated through),
but you can try their demos before using,
or request a personalise demo from the tech-support (eCom and such),
install it, and run some tests to be sure it suits you (and then buy it).