I like the Eheim and it was my go-to for many years before I started using Apex a few years ago.
The Neptune AFS is very similar to the Eheim, just connects to Apex, which I like for ease of programming and remote activation. The main reasons the Apex AFS gets bad reviews is because it is ridiculously loud, and it is old tech they got from another company and just made a wired connection to the Apex (as opposed to coming up with something better) and then charged twice as much for the connection. It’s annoying, but having it connected is worth a lot to me so I use it.