If you want an AI audio foundation to make music without hiring session musicians, Kits is a good option. The service has a broad range of AI tools, including voice cloning, AI singing synthesizers, vocal removal and mastering tools. It also comes with a library of instruments and a range of API connections, so it's good for music production. It's got a free tier and several paid tiers, so you can pay for what you need.
Another option is Musicfy, which lets you create music with different voices and that has a range of other features like AI voice artists, custom voice creation and text-to-music conversion. It also offers royalty-free music albums you can use in your projects. The interface is pretty easy to use and the tiered subscription plans make it a good option for both casual and serious musicians.
If you're more focused on mixing and mastering, Cryo Mix has a collection of AI tools to try to make your audio sound better. That includes tools to correct pitch, add backing vocals and adjust dynamic EQ for a more polished final mix. The interface is designed to be easy to use and accessible to people with varying levels of audio engineering skill.