I have always been in the market for mid-range electric of around the price you mention. I've never had a lawn that seemed big enough to bother with petrol, and I don't trust cordless to not bog down due to lack of power.
I have had mostly Flymo or Bosch, and my vote would strongly go towards the Bosch Rotak too. Each FLymo I've had has sounded good, and seemed to have good features. But they've all been badly implemented, and the mowers have been not terribly well put together.
Examples:
A grass collection bucket within the body of the mower for compactness. But it means the design for airflow is less good, and it clogs up very easily, Tend to need to empty it twice as often when it's not even full.
An easy to use height adjustment lever. Except it works on a system where it slots into one of a series of notches. The notches and the lever itself are both made of a plastic lacking in durability, so after a season of use they've rounded off and it regularly slips out, drops the mower to its lowest setting, and scalps a round patch of your lawn. The last few years of its life, the mower had a bungee strap holding the lever in place.
Oh, and when I complained about the stupid lever design they were completely uninterested.
When I finally gave up on that mower, I moved to the Rotak, and it has been simple, effective, and done what it's supposed to for 3 years now with no problems.