Go for a Fantom 8.
I have the 7 - but also an RD2000 (which has the same keybed). I already had the RD, and thought about the 8 - but its 10kg heavier than the already chuncky RD and I gig a lot - hence added the 7 rather than replace the RD with an 8.
Sonically - for piano - its personal. I like it but a lot dont. BUT its the best piano/graded hammer action keybed available. Its got a lot of synth stuff onboard, and the way it integrated with other hardware and VSTs with its zonal system means you can add a piano VST later if the onboard ones dont work for you.
Seriously - as the "brains" and Controller" for either stage of home use its unbeatable. Yes it has issues (some dont like the sequencer as its pattern based, the rhythm/drum machine has only 2 times signatures, not a lot of stage for onboard user samples - and the aftertouch is stiff on the 6/7 and prety unusable on the 8 etc) but what it does do - nothing else can at present.