Hi,
The answer is easy!!!
1. Take the gun to the range and shoot each one very carefully . . . at the distance you like your self defense guns to hit when zero'ed for self defense purposes. I'd bench rest it first, then verify that you shoot at the same point of aim when shooting standing/unsupported.
2. Then, buy the one that shoots exactly to point of aim at that distance!
3. Then, buy a couple of other brands in the bullet weight that shoots P.O.A. best . . . and see which of the three groups tighter.
4. Buy the one that shoots the tightest groups to P.O.A.
Hope this helps,
Tom
PS: Generally, the lighter the bullet, the LOWER it will impact on your target, even at ten yards. Sometimes the difference at that range can be several inches if the bullet weights are much different.
This is because the lighter bullets are faster leaving the barrel . . . before any recoil motion gets started. The heavy bullets like the 180 in your case, MAY shoot much higher than a 155. Different brands and/or bullet types within the same bullet weight usually shoot to different spots too, somewhat.
You surely don't want a bullet weight in whatever kind of gun you are shooting to impact several inches higher or lower than you think it is . . . and you can't depend under stress to "remember" whether to shoot any specific gun higher or lower than what the sights tell ya.
Both loads you mentioned are effective . . . as long as you put that bullet exactly where you want it to go! Bullet placement trumps the loading.