Hey John!
I would echo what Junior said above. All of those areas have something going for them - it just depends on what you're looking for. I know people have had luck in the Ooltewah area with renting to "company" men who are looking for part time housing and there is an Amazon plant there so there is a good about of hourly worker looking for places to stay close by. In East Brainerd you will find the sprawling suburbs. There are malls, chain restaurants, and many businesses and also a labor and delivery hospital. It seems Redbank is gaining popularity with young couples. It close to downtown and offers a neighborhood feeling whole being close to the city. Hixson is not an area I know much about but I've heard of people having great success with flips in that market. It does have a mall and lots of churches/activity. The general business district saw a decline in the recent decades but is now getting revitalized as of late as I know some new restaurants coming in!
There are a ton of other places to explore too - most notably the Ridgedale Market. It's a small neighborhood just outside of the city. It's projected as the next big boom in terms of "not quite city" single family and duplexes. It's certainly less developed than the areas mentioned above but its worth mentioning if that's something you're interested in.
I've lived in this area my whole life and just started to get into the investment realm. I would love to be your boots on the ground - referring agents, going to open houses, or doing drive by's to get a feel for the house. Any time I can learn more by doing, and help another investor I am all in! Shoot me a private message when you're not busy and we can continue to talk neghborhoods!
Best,
Lindsay