You need to compare vs same supply worth of archers.
So 4 archers is 80 dps, so they do half the damage that a wizard does.
However, 4 level 5 archers is 800 elixir and 1 level 5 wizard is 3500 elixir. That is 4.375x the elixir cost per supply.
Also, while archers are more susceptible to splash, wizards are more susceptible to single target damage, as you can only single target 1 archer at a time, making 4 archers take 4 shots, and 1 wizard only able to take 3 shots (156hp vs 56-65dps from most decently leveled TH8 defenses).
This gives you a trade off between the two, and the wizard SHOULD be the better unit, it is t2 and way more expensive.
I agree, 3m would be a good trade off between the two. You're looking at 45s per supply to build at 3m. That is double the build time of an archer and 4x the elixir cost of an archer. Seems MUCH more balanced than anything listed on the poll.



