It all depends on where you sail and what type of boat.

In Galveston Bay I had a 35' Jeanneau with a 150% genoa. The Jeanneau had a smallish 16 SA/Disp rato. But the jenny was too much for the wintertime conditions there- you can sail year round in Galveston Bay. I wish I had had a 130% genny. But later in the summer with its light winds, the 150 jenny did fine.

But in Southern California where I am now with its lightish winds (but not today- a storm is moving in with 30 kts or better forecast), a 150% genoa would be fine on the Jeanneau. But I am now sailing a J/32 which already has a large SA/Disp ratio of 21 with a 120% genoa. That combination works well here in SoCal with its lightish winds.

Also another consideration is that a smaller genoa will usually work better to windward, but will lose out to the bigger genoa in light air off of the wind. The best rig that I have sailed is the Saga 43's so called solent rig- two headsails on parallel furlers. One full cut genoa for reaching/running and a flat 100% self tacking jib for going to weather. The only downsides are the cost and a bit of windage loss with one furled headsail in the way all of the time.

David