Do you really like to vacuum?
My guess is that you're probably looking for something that's easy to live with, easy to use and highly effective.
I only asked that question because you never know what kind of recommendations you'll get when you ask online. Not everyone has the same "vacuuming styles", preferences for the same types and brands of machines, or even the same fondness for what others consider to be a mundane housekeeping chore. If this sounds like a disclaimer, that's only because it is: We are vacuum collectors and most of us LOVE to vacuum - probably more than we should. We love to take in the unique features of different brands, sometimes we're a bit myopic and tend to prefer one over the all the others.
I suggest that you look around before buy your next one. Check out a few videos on YouTube of the different models and brands. There are plenty of private individuals who have made demonstration videos of the various machines in real world situations. It's important to see the good, bad and ugly of each machine.
There's nothing wrong with the Shark brand, as long as you understand that you'll be performing routine maintenance on filters, because these machines are bagless. The Flex Duo Clean model you chose probably isn't substantial enough to pick up the kind of dirt that makes its way into your home on a biweekly or daily basis. Look at one of their full-size uprights. Many of them now have anti-tangle brush designs and even fluffy heads for the bare floors. The Aerus/(original Electrolux) suggestion isn't a bad one either, but I strongly suggest that you see it in person at a vacuum shop that sells multiple brands.