Federal Fusion 95gr and Power-shok 100gr have a great reputation in many .243 Handis and Ultras here, they both shoot moa or better out of mine. Statelinerut has used the Fusion on deer for 2 yrs now, and popped a coyote or two also.
Mac shot the Fusion ammo in his .243 that he sold to Mitchell, it shot moa or better in his too. Myarmor also shoots the Fusion and Power-shoks in his. I wouldn't steer ya wrong, they work in a lot of .243s here, but it seems that some shootera have the best luck in factory ammo with either the heavier or light bullets, only one that I know of that likes both ends is Mitchell's, but he handloads for his.
One that didn't shoot too well for me, 1½moa or so which is acceptable for a lot of hunters, was the Federal Vital-shok 85gr BTHP, but others have found them to be very accurate in theirs.
Each rifle is different, just because someone gets really good accuracy our of one brand of ammo, doesn't necessarily mean it will work in yours too, so don't buy a lot of one kind of ammo, try 2 or three different kinds of those that have been recommended.
It doesn't hurt to do a little pre-range cleaning and finishing on the bore to save some range time and money on ammo, some barrels shoot well out of the box, others may need several boxes of ammo to shoot well, doing a little bore polishing as described in the FAQs may save you some time, money and frustration.
Tim