My first house was a flat, quite large lawn and dad was moving to a flat so I got a petrol model with geared drive from him. Benefits - easy for the cutting as it pulled itself along, other than that it weighed a ton to move around in the garage etc.
Moved to a house on a bank/hill and the petrol model was useless, no grip to get up the inclines so I went to a rotary mower, cabled electric. Way easier to use on the slopes but a faff with the power cable. Moved over to a Ryobi battery rotary and it was a mix. A little heavier with the battery but so much easier to just get out, use and then put away. Much faster as you can move about freely without fearing for the cord. I borrowed a self-driving one but it was all over the place as the lawn was not flat.
Feedback from a neighbour was that the automatic ones were good on his front lawn which was flat but he had to put a number of markers(?) to limit it's freedom which he found rather expensive. The results were good on a clear lawn but the bucket was quite small and so repeated use with short cutting was the order of the day. It did do the full garden on one cut (and a couple of emptying runs it did itself) quite easily. It was fairly quiet but he tended to still only run it when he was around to keep an eye on it as it was the front garden. He did have an issue with the local cats, most thought it was Satan but one kept sitting on it when it was working which caused the alarm to sound.
For human operated battery the trade off seems to be higher powered battery is heavier but has more grunt to do the job without retracing your steps. I tried an 18v mower and the 36v and went with the 36v which was heavier but did a lot better in one sweep. The ability to use the batteries in a selection of tools tends to mean you end up with a couple of batteries which give flexibility and enough grunt if you forget to charge one. Useful tools to mix them with were a water jet blaster because you could just fill a bucket and give something a quick blast. A leaf blower/sucker was quite good but the cabled powered one I had was significantly better for sucking wet stuff.
