Lawn mower specific oil is usually over priced basic conventional. For lawnmowers specifying a 30 grade such as 10w30, 5w30 or SAE 30 I would recommend a synthetic passenger car oil in the 10w30 grade.
My favorite is Mobil 1 High Mileage 10W30 which is a little thicker than most 10w30 and also has a boosted additive package. The regular Mobil 1 10w30 is also a good choice as well as any of the 10w30 synthetics from the major players including Pennzoil, Valvoline or Castrol