I tried open cart and hated it.
Shopify wasn't that enticing to me but i think I'd rather go with that. We also tried big commerce and that too was horrible for us.
Initial setup is usually the biggest pain with any new site. Maintenance overall is big too. You need time and money to put into it to do it right. I need to tweak things on our site, but i simply don't have the time right now. That was one of the realizations I came to when I decided to move forward with prepping it to sell the company.