I used a gravity/siphon method on a 12 gallon covered cube when I couldn't tend to it for more than a few days (out of town). It took some fiddling - I found I had to use 3/8 air inlet tubing at the water line and cut it slashed - or it would just suck up water without breaking the vacuum. But once I got it working, it worked fine. I just used gallon glass milk jugs, so it couldn't overflow (much), it was cheap, but I did have to restart the siphon every time I added water. For that situation, it was the right tool.
For my current system, I've got an avast ATO with their peristaltic pump. I've had it about 2 months, but so far, it's working well. It too took some fiddling, but only because I used a peristaltic pump with a float valve - so I put in a recycle loop. The magnet mount is very convenient and adjustable, and I suppose if it does fail, it would fall in, and stop the ATO, rather than encourage continuous pumping. I like it. The pressure sensor works well. All the tubing connections have to be tight. I had to address that on set-up, but not since. If I had a second large tank, I'd buy it again.