All Yamahas...
PSR-510: Cute little keyboard that lit up like a Christmas tree when you turned it on.
PSR-4000: The 8000's little cousin. Especially loved the wheels beneath the screen. Yamaha replaced them with buttons in later models. Not sure why.
PSR-9000.
9000 PRO: By FAR the best key action I've felt on any keyboard I've ever played. Still my favorite of all offerings on the market today.
Don