I'd go for a Cup.
For one it's cheaper to run and it doesn't have Xenon's and doesn't have A/C so servicing is cheaper (cambelt work and air con issues)
Number two, it's lighter, even if only marginally I like knowing that an attempt has been made to make this a classic small and light hatch. This also means marginally better performance, again not noticeable but there you go.
The seats are good, but they don't look as good as the full leather ones and possibly aren't as comfortable, but they are comfy enough and still offer support.
It depends if you can do without the A/C (a plus for me), no Xenons and no posher looking seats. There will also be marginally more road noise due to the weigh saving measures. The choice is slightly more comfort or slightly more raw driver's car, not that a 172 isn't already, far from it. The latter appeals much more to me.
There is no such thing as a full fat 172 though, so don't know why some people mention that term when discussing 172's.