Consider Requirements and the future
Magento is currently the most singlar popular solution being activily used in 2015. It has nearly 8 times more share than Wordpress WooCommerce (even though Wordpress Designers tend to confuse cms usage with eCommerce use). Magento is also has the fastest grow of any eCommerce platform.
So what is all the fuss of Magento
Magento is one of the first out of the box eCommerce solutions that can handle 50,000+ users, 100,000 of products and 1000 Categories. It is also incredible flexible, for example to date Mebsites has built; classfieds, debt collection register, realestate listings, eLearning/Trainning, eBay style multi vender systems, Subscription based controlled websites all using Magento as a backbone. None of these monsters even resemble a classic eCommerce store.
Support and quality of the core software is fantastic. The extension (Plugins for WP people) are of a high standard and most are geared towards increasing sales and productivity.
One of the really exciting things is you can break the site down into components and house the different parts in different servers. It gets crazy complex from here so I won't go into it. But lets just say its an ideal platform for a mega sized global store.
Magento is available as the Community or Open Source version or Enterprise and there is little difference between the to at the software level, rather with Magento Enterprise having world class support.
Well thats great Aaron, but we are only small
Small or big doesn't matter. The Calculation you should be running is this; Setup cost vs future expansion (products or users).
If you go to the Big Magento Enterprise firms you will have a heart attack when you here the price. Most won't even let you book an appointment unless your spending upwards of $100,000 AUD ...yes that is not a typo! You will get world class industry leaders excessive planning every detail of the site for you on an epic scale and most likely fancy coffee and muffins during your meetings.
This is of course well out of reach for a small business. Most small business end up looking to go with Wordpress, Magento or more managed system like Shopify. All are pretty good solutions for small business, with Wordpress the least suitable due to security issues.
All three and most eCommerce solutions all cost around the same money to develop, with cheaper template options as well.
The difference is what happens after the basic step. All eCommerce website startups and small eCommerce want to do well and most wish to expand. Success leads to expansion and improvement then reinvesting into your eCommerce platform as it proves itself (when I mean proves itself all the platforms are pretty good with the getting traffic side being slightly better or slightly worse. No platform is a traffic magnet itself).
So the eCommerce store is a success you are getting lots of traffic, I assume Website hosting is expanding as needed. Now you want to improve average sale, increase the product range, start adding promotions, newsletter followups etc. This is where Magento really shines because all the tools you need are there already. Yes you can add plugins to wordpress as well and there are a lot of them. However, you'll be more worried that your Wordpress site is now starting to choke on traffic. Your getting 50-80 users simultaneous and lots of users are complaining the site is slow to load and sometimes it doesn't load at all. You add plugins and this only seems to make it worse...welcome to the limits of Wordpress. There is a very finite limit to Wordpress and most successful small store owners find it pretty quickly.
Shopify handles the traffic no problem, its lite and simple which is great to get you past the learning curve. However now traffic is increasing you are struggling to manage orders, products efficiently. More plugins...hmm the pool is very limited and most are bugggy and really just don't seem to be well designed or for any real purpose, but to promote the maker. The plugin resource just aren't there. Why Shopify is relatively under funded and doesn't have the high end developer support that Magento does. Consequently, you are on your own if you want something more than social media links.
So both Wordpress and Shopify with limited success and still being a small business you are having to look to re-develop a new eCommerce website solution. (I won't even touch the if you want to build something square/outside the limited/round whole of these two platforms).
So with Magento startup pricing is very similar sometimes even cheaper as there are less constraints. Best of all as you grow you can add features and change the styling anyway you wish knowing that only when you get to mega mega sized eCommerce you might have to think about redesigning Magento for even more compacity.
So while Magento is a little over kill short term for a fresh new small eCommerce website. Few people end up loosing money because of an excess of features and flexiblity.
Note: I didn't cover hosting costs or Shopify's monthly charges for its packages as they are all fairly similar when you take it as a whole.