A combination of games, and hardware revision. If the launch version of a console doesn't have any games, and has poorly thought out, overpriced, hardware I'll skip it. Sony systems for example have always been worth waiting a year or two for instead of getting out of the gate.
I got a Switch early, because the price was decent, it had plenty of games, and the hardware (portable-console hybrid) was a genius idea.
I think these three things are ultimately what motivates most people to get a new system. I mean look at the XB1. It lacks exclusives, was $100 more expensive, and came with Kinect (poorly thought out hardware).
Or look at the PS Vita, and 3DS. Both systems were expensive at launch, both systems lacked games, and both had a fair share of hardware design hiccups. Luckily Nintendo righted the 3DS, with the XL model, a nice price cut, and good games.
If 3DS had launched with a $200 2DS XL model, Mario Kart, and 3D Land it would have been in a much better boat from the outset, sales wise.
