I’ve used
Prestashop. It’s ok but it’s templating system is SMARTY based so you have to spend a fair amount of time learning about all the .tpl files that make up a site. I think the payment options might be limited.
Other than that I’ve used Ditto to make up a product system and send it to FoxyCart but again there are limitations in the cart/checkout system. It’s nice but not spectacular. The other alternative is to just use Ditto for products and use PayPal.
TreasureChest was a dead end and very frustrating. The other MODx based solutions are all good efforts but incomplete. This is no surprise. It’s a huge undertaking.
LemonStand looks promising but is not yet available. MODx is mentioned by one of those who has been testing it and trying the demo it all looks quite right. Can’t wait for it.