Amazon FBA Software That You Would Recommend?

I’ve been researching different amazon FBA software options lately and wanted to get some real feedback from other sellers. There are so many tools out there now and it’s hard to tell which ones are actually worth paying for versus which ones just look good on the surface. Has anyone found any solid tools that feel close to free Amazon FBA software in terms of value; even if they’re paid but affordable? I’m especially interested in anything that helps with product research, sales estimates, and tracking keyword or market trends without a huge monthly commitment. Would love to hear what you’re using and why it works for you.