the higher level monsters, teh better the drops, a lev 5 monster will drop lev 5 gear (wolves, sasquatches etc) but a lev 50 monster will drop you lev 52 gear (cerebrii, salamander ruin, etc)
for me, best drop rate has sand golems... i got every hour like 3 hs, 10 armor pieces and around 7 ms, like 4 soft sand and 4 tool aids