Plenty of really good suggestions here, but I don't think it makes it easier for you to make a choice. Here's mine, based on experience:
"Start small, then scale up".
I've used WordPress, Joomla!, Drupal and Magento for e-commerce websites. It is easy to recommend a platform if one is comfortable with it, but from the sound of things this is probably an early experience with e-commerce platforms for you. For that reason, it is important to minimize the complexity, so that you can focus on the important things: sales and profits.
So, if you have a 10000 product inventory, head straight for Magento, but be prepared to budget at least 35% of your profit for a developer. Even changing a Magento theme will require some expertise.
If you have a smaller inventory, I would thoroughly recommend WordPress and WooCommerce. Barrier to entry is lower, and support is readily available. Some may feel that WordPress is not an e-commerce system, but that depends on perspective. E-commerce is buying and selling. Bottom line, you get paid. Does it matter what platform you use? Not really, as long as cash ends up in your bank.
The problem with dedicated e-commerce platforms like Magento, is that they need big budget support. As a small to medium sized business, you might be more interested in your overheads. WordPress+WooCommerce is certainly the way to go, if that is the case. Because they are 100% FREE. (as are Magento, etc). But the support investment in man hours and potentially expenditure, is considerably less.
Once your e-commerce store has taken off, you can consider expansion of your 120000 strong inventory into Magento. Although you may not see the need at that point.
Hope this helps you.