From the harvesting I've done it seems chainsaw is a good option as it harvests more than my Carcha. This is a 260.8% ascendenct chainsaw also. Ihave also noticed that dinos that give more of other resources, e.g. Prime meat do not give as much as a corrupted stego or ptera which is interesting. Haven't tried gigas or reapers yet but so far ptera are my go too since they overspawn in the tar pits. A paracertherium gave me 50ish corrupted nodules while ptera give around the same. However Spinos seem to give more so still unsure what's the best to harvest yet.