The best all around bullet in the 300 WSM is the one that shoots the best in your 300 WSM.
Having said that, I agree with LTLR that the GS HV 177 is at the top of my list for the best 30 cal hunting bullet, especialy for LR. But before anyone goes and buys them, make sure you have the twist for them. A 10 twist is borderline them and a twist of about 9-9 1/4 is recomended for hunting at all ranges. An 11 twist is OK for greater than 500 yd shooting. You can probably get away with a 10 twist with higher velocity cartridges. I think they recomend the higher twist for closer ranges to ensure terminal stability.
GS CUSTOM BULLETS - Specifications for use
Other than GS bullets, my next pick is the 180 E-Tip, and I think 180 gr bullets are ideal for that cartridge, especiay if we are talking LR.