The piano that I use is a Yamaha P155 Digital Piano
There are other options out there and I did try out quite a few option before deciding on this one. The options were a Korg sp170 (with a newer 'S' model out), a Yamaha p95 (also a newer p105 model is out) and a Casio px-130.
Yamaha Keyboards use 3 different kind of weighted key actions.
The first is the GHS (Graded Hammer Standard). The next step up is the GHE (Graded Hammer Effect or sometimes used to be known as 'GH'). This is a slightly better system with weightier keys.
The Yamaha P95B
uses the GHS and its not until the YDP-161 and the p155 do they start incorporating the GHE system. I prefer the GHE as it's heavier and has a nice response to it. The GHS felt a little bit light and not as responsive to me although some people prefer that.
The Korg SP170s
had a nice heavy feel to it. i did like it but it was a bit too heavy and side by side with the yammy p155, the yamaha one hands down. Yes its more money so you get what you pay for. There is also a Korg SP250
which someone at my workplace likes but wasn't to my liking. I think it was good quality but just a bit light for me.
The Casio was nice as well but the keys wobbled a bit from side to side and didn't come back to rest position as smoothly as the yamaha. They were ok to press though.
Feel free to have a look at the from the links specs below and post in the comments if you want to ask questions.