Which level 5 monster is the best?

Dendroids are very good in my opinion. In "cans" and especially Dragon Utopia. Because they are very cheap, single-cell (blowthrough!!!!), have abilities naturally, and besides, you don't feel bad leaving them in the utopia!!! Meaning, like, there are unicorns, maybe dwarves (meat for the cancel), something else (for example 24 wyverns or 6 angels), plus some completely random meat - and an impressive stack of dendroids. If you're lucky, unicorns and maybe wyvs/angels come out of the utopia.