I use lot's of Hornady bullet's now but am ready to give Speer a try again. Nothing wrong with Hornady's, great bullet's!
Year's ago befor Vernon sold out to OMARK I used Speer hot core's in 7mm Rem Mag, 280Rem, 308 Win, 25-06 and a 243 Win ( never cared for the 243 but still have one). Here's my experience with Speer hot core bullet's. One of the best bullet's on the market. I did penetration test's into bundles of newspaper at 100 yds and found that Speer's maintained 86% of their weight(if memory serves me). The difference between them and Hornady's is that the Speer bullet's didn't shoot loose in their jacket's. I've used Speer and Hornady's on a lot of deer, a few elk, a few antelope, a few black bear's and lot's of varmits. If either brand ever failed, I haven't seen it. I've also used Herter bullet's (defunct and probally good thing) and Sierra bullet's on game. The only failure I ever had with either was a 140gr Sierra out of a 7mm Rem Mag at abour 60 yds on a black bear. More a problem of a bad choice of bullet than a bad bullet. But I never liked how the Sierra bullet's tore up the inside of game so quit using them on game. They are fabilous on varmits and target shooting.
I've shot a few Nosler's but not enough to give an opinion either way. The only thing I use them in now is my 243, the 70gr bal tip. I would suggest you use a heavier bullet for game, deer, in your 243. I believe most people that have bullet's fail have tried to make a to light bullet do in to hot a cartridge do to much. I've heard good thing's about 90 gr 24 cal bullet's on game but stick to the belief that for game that the 243 is suitable for, the 100 and 105 gr bullet's are best. Keep in mind, I've only shot a few deer with a 243, not my favorite cartridge. Keep in mind also that there is nothing magic about a bullet, you live within it's capabilities and it will preform.