Out of the people I know that use 280's, most use the 140's. But then again, they aren't shooting anything bigger then deer. I would say use which one your gun likes the best.

Ifyou want a 140 gr bulletI'd suggest the Barnes TSX. I use the 140 tsx in a 7mm rem mag, performed awesome on both elk and moose. In the .284 cal. I have also used Nosler part, AB, Hornady Interloc SP and Failsafes on elk/moose with good results. Other then a barnes I'd be looking to a150gr +premium bullet.

As mentioned prior pick the best accuracy and bullet for the job, IMHO the 160 AB is better suited then a 139 IB and would give up some to use it or equiv. Since it is the better grouper it makes the desicion a lot easier and will also help in weighing the results of your chrony testing.

My choice would be the 140gr tsx.It out penetrates partitions of 160gr and 175gr..

Just about any bullet will work on "deer sized" game including elk, as far as the .280 Rem. I've had good results with the Winchester Fail Safe's over the Nosler Partitions. I had Federal premium in N.P. on my first hunt with my .280 and the deer ran off with a broadside hit behind the shoulder. I racked the rifle the rest of the season. The following year I switched to Win. Fail Safe's and dropped an 8pt where he stood. Every deer since then has either dropped in their tracks or not ran over35-40yds.
The Fail Safe's or the Grand Slams would be a better choice over the N.P.'s, also the Swift A-Frames are a good choice.