What I would like, if I were collecting.
A subset of-
Young stars: Have only one star player per team and do away with star signings, then have the young star of the team as a shiny, for example: Martin Kelly for Liverpool, Oxlade Chamberlain for Arsenal.
Legends: Do away with showboats/golden moments and have legends. They'd be so awesome, great to find out about past players and could have boosted ratings to really add to your team. Only issue would be teams like Arsenal/Man United/Liverpool/Everton etc.. Who have LOADS of possible legends, it'd be hard to narrow it down to just one. Dalglish stands out for us but he'd be a manager card so..
Stadiums: These would be nice, seen as the manager goes on the team page now, this could too and there could be less player base cards, only issue is that they'd look better horizontally than portrait..
Kit cards: Always said I wanted these, just home and away, no third kit, they'd be a really neat addition.
Of course, some of these could always feature in the Extra set too!