I usually go digital if the game has no physical copy but a cheaper price and special bonuses are tempting to me.
I recently purchased Tales of Hearts R digitally on my Vita because it had bonus costumes included that was not in the physical copy and I almost purchased Disgaea 4 during the PS Anniversary sale but I just didn't have enough money.
Edit: Price drops on physical copies doesn't happen too often here in the Philippines and it takes years before the retailers bring down the price of a game. So a sudden sale online can become a cheaper alternative.