Shopping cart/Store plugin needed

I’m looking for a store/shopping cart for wordpress. I’ve seen quite a few that are nice but seem to lack some of the things I need. A major thing I need is the ability to add custom shipping options such as custom box dimensions. A lot of the them only allow you to pick from standard boxes and stuff like that. I also need a lot of options as far as payment gateways. Anyone knows a good option for me let me know.