Playable League or Custom Database?

which option should produce the most available players. because for some leagues that arent readily available, but do have club teams in the game, loading all players from top clubs in that nation opposed to load all players from nation, seems to produce more players in the game. i think its something that needs to be worked on in future editions of the game? because for instance now I want to start a quick couple-o-season save and am stuck in thought thinking which leagues/custom database to include so I have a varied option of known or decent players rather than an abundance of greyed outs.