For such a small yard get a walk behind push mower. It propels itself, all you have to do is keep it on line. It will really frustrate you with the amount of your yard that you cannot get to with rider mower. the corners, landscaing, etc.
With a walk behind mower, you will have to do very little if any trimming with a weed eater. With a rider mower...a ton of weed eating.
A top of the line walk behind mower will run 700 to 1 K tops. A decent rider will run 4-7 K.
What happens if the mower needs work? With a rider, you need a trailer to get it to the repairman...with a walk behind, put it in the back of a truck or SUV.
Trust me a walk behind, with such a small yard, is the way to go and save 4-5 K!!! If your time is the main factor, by the time you frustrate yourself with a rider and trimming, you can mow it with a walk behind...