When I talk about gear it is important to think of the software and that choice is probably the easiest. Adobe Photoshop Lightroom I would say is a must have, it not only allows you to adjust images but it also catalogues your photos and backs it up online. I have some videos showing you how to do that. Lightroom also works not only on you Windows PC and Mac but also on your iPhone, iPad or Android phone or tablet. What’s really cool is if you make a change on you mobile device is updates on you computer too.
Photoshop is useful too, thankfully Lightroom and Photoshop come as part of a bundle.