First of all, I develop for and like Open Cart, Woocommerce and Magento. Actually, perhaps humorously, I prefer WooCommerce out of all the platforms I've listed! The main disadvantage with Woocommerce I find is having to use Wordpress Taxonomies to build any custom queries and occasionally writing plugins that don't exist.
Sorry, what do you consider regularly patched?
It's not a good thing to have one person oversee a project, or is it?
Using Trellis as a mediator here. trellis.co /blog/magento-community-vs-opencart/. You can make complex code for Open Cart, but it's uncomfortable. At least for me personally it's better to use Magento, even Woocommerce for anything complex, over Open Cart.
The UI is difficult to customise in Open Cart as I said. What I wrote did also require some involvement with MVC, but I didn't want to rewrite a lot once I gave users roles, it was just for user experience, I just wanted to hide and block access to anything irrelevant as all authenticated back end users were trusted ones. I could have done the hiding part with CSS.

Obviously the easiest platform for this is WooCommerce anyway, as Wordpress has a fully feature ACL.
Each to their own though. I haven't a preference. Neither of us know what dovroc is looking for

, so there's no need to really debate which platform is best.