Personally, I started out using Corelockt, then 100gr Hornady custom Interlock BTSP, then Hornady SST Super-performance, on to Barnes TSX.
I've now rested with the XP3 and doubt a better bullet for the 243 will be developed in my lifetime. It drives that perfect performing 95gr bullet deep or through
the animal with outstanding damage. I'm getting just over 3000fps with my 20 inch Model Seven Remington. I feel these new projectiles change the the way
many calibers perform. I'm a promoter of the new generation of projectiles coupled with velocity. When you can shoot a 200lb animal with a 95gr 243 and have an
exit hole bigger than a golfball its amazing. I've larger exit wounds sometimes than a 450 marlin.
If you plan to shoot over 200 yards or so, I'd recommend two bullets in the above list for best performance on game, either the Hornady 100 gr interlock or the XP3
I still believe for game animals, the 243 is a 200 yard gun to get the max performance.
Added: The 95gr XP3 243 produces slightly better instant shock and knockdown results on animals than my 35 using 200gr Leverevolution. The 35 LTD is still my
favorite carry rifle.