Good advice so far, in your shoes I'd choose between the 1100 and the Berettas. The Berettas may last a little longer, but it's a moot point if they both will outlast you. Over on the Shotgun Report, the guys say that 1100s start to really eat parts around 35K rounds.
One small quibble, the 870 is quite suitable for trap. One shot at a time,so the pump action is at no disadvantage. The 870's a superb trap gun, and will outlast you, me, an 1100, and any Beretta you care to name.
FYI, I shot my very first rounds of trap doubles today with my 870 TB at the Geezer League.39/50. Might have done better if my front bead hadn't left at Post #4.
I hear people say that the 870 is a hard kicker for a trap gun.At least some of those folks need to work on their form,as a few minutes observation of them shooting will show.
But get what you want. Life's too short to go without a good trap gun(G)....