Short castling if my advantage is a time advantage, long castling if my advantage is a space advantage, no castling (as Black) if my advantage is a locked center and strong counterplay on the flanks with time compensation for White's space advantage. In general, anyways.
Short castling or long castling?
Short castling as it's neater and I usually don't need or want a ready-made instant attack down the other side as long castling often tends to have. Obviously if it's clear a long castle is better I'll go for it.
For the openings you play, what way do you prefer to castle?