For the powersupply, basically its the same as long as its great brand.
But for corsair never touch CX because a lot of people had problem, so as long as its gold and 750W it should be enough.
Well, samsung is an awesome brand for SSD / HDD so it should be okay. and yes it was the cheapest on 256.
Your processor is the best you can get, and the motherboard is the best one also. (Just curious why did you pick the maximus mobo? Did you want to overclock or what. Cause if you didn't use that much, Z97 can overclock also with a cheaper prices) Before this Rig's im using (MSI Z97 Gaming 3)
http://www.tomshardware.com/reviews/best-intel-amd-motherboard,3902.html
Maybe that link will give you an insight.
Also did you play on 1080p/1440p/4k? Single, Dual / Triple - Monitor?
Graphic Card GTX 970 had VRAM problem which 3,5gb primary and 512mb secondary which is way slower. Yeah it was 200 bucks different. The power is also different.
http://www.bit-tech.net/hardware/graphics/2014/09/19/nvidia-geforce-gtx-970-review/10
If you are really into gaming, i suppose you will see that it will be a big difference, specially if you are playing on higher resolution. But if you stay on single / dual monitor 1080p or single monitor 1440p. 970 would be enough.
Well the truth is, i was giving you GTX 980 suggestion because, you did pick the "BEST Motherboard", Usually people most concern on PC are, Processor > Graphic Card > RAM > Motherboard.
Also what r u going to use this computer other than gaming? Design?