I dont have a 300 WSM or WM.. but I do have a 7mm WSM and have owned a 7mm RM previously.. (as well as a 300 WM)...
140 gr Barnes TTSX and 150gr TSX both do extremely well in my 7mm WSM.. they are about all I load for it anymore..
A lot about what would be recommended will depend on what you intend on hunting, and where..
Most here will agree that if youre talking a big bodied animal in Africa (eland, etc), to go heavy for caliber, and to go with a premium bullet like an a-frame or a tsx, etc.. regardless of the actual caliber of the rifle you are shooting..
If youre talking about taking your 300WM out on a mule deer hunt in NA, you'll probably get a much more varied response out of folk.. and much will depend on where you are actually hunting (are shots going to be at 100 yards, or 400 yards, etc..etc..)..