Bull Rush does only a % damage to main target. You make up by splash, so when there is a single target on row, use another attack option.
Use Bull Rush 1 (40% damage) when there are 3 opponents alive on same row and Bull Rush 2 (50%) and Bull Rush 3 (60%) when there are at least 2 opponents alive on target's row.
Attack the weakest target in a row when using bullrush, maxes damage
Beware when there is an assassin in the row as they have evasion(chance to dodge splash), if you can win against the assassin better to target them as main, even if there is a weaker person in the row.
Right way to compare the damage is to hit the same target. I know it's hard.
Titan and Enforcer should have the same damage over the same target, if using normal attack.
Bull rush reduces the base damage to 40/50/60% and the dmg on main target will be significantly lower, in exchange of 2x splash damage on the adjacent targets.
As a titan you don't have much base Attack, so hitting someone with no defense, your damage probably look okay, but hitting someone who has more defense than your attack, your damage will be reduced very hard, even if you win.
In the next client version, we will have a feature to show you how much damage roughly you can do to the target and how much damage you will receive from different attackers.