Personally I prefer LoI.
Both games I think are far from perfect, but LoI has for me contained more replay value.
CoD was, for me, a chore to finish (including Trevor's game). I found the Innocent Devils, while an interesting idea, poorly executed.
While both games suffer from monotony in the gameplay, I found LoI's easier to bear. I think it helps that LoI's whip combat system has some depth to it, some variety. LoI's short length is ironically another plus.