Mannedorf is a lovely town.
(Why has EF suddenly stopped accepting my umlauts?

)
I lived in Mannedorf when we first arrived, stayed there for 5 years. Excellent train transportation to Zurich and to Rapperswil in the other direction, easy car commute into the city as well.
I was so fortunate in my neighbors - lovely people who have remained good friends. The town had a very open vibe, I always felt welcome - even though I arrived with no German at all. Several of my Swiss neighbors had themselves lived abroad, understood the challenges a foreigner faced and went out of their way to be kind.
The town has a decent infrastructure - as mentioned, good train connections, a couple of decent restaurants, a nice swimming Badi, an even nicer unofficial swimming spot by the second harbor where the dogs were welcome, a fantastic coiffeuse (my former neighbor

) the best mechanic in all of Switzerland (another neighbor

) a small Coop and Migros, a bakery... and Kino Wildeman, a little gem of an art house cinema.
And the lovely Pfannestiel hiking area.
No, there is not the nightlife one would find in the city - but you are only 20 minutes or so out, you can always go and find the bright lights - and then come back to your friendly, convivial little town.
I was very happy in Mannedorf - I'm sure you would be as well.
Good luck in the house hunt.