How to choose a better minion?

There are several ways to decide which minion to put in your deck. One of the ways is based the stat of the minion. Stat simply means the total of attack and health of minion that you can summon per mana spent.

The diagram above shows common minions card with pure stat and without specific skill  for each cost category.

So the basic formula for stat = 2*cost+1

By having 2 mana, you can summon common minion with total 5 stat maybe a raptor with 3att and 2health. So if you can summon a minion with more than that, then it is a beneficial. For example a warrior with a fiery war axe can summon a Bloodsail Raider with 5att  and 3health a total of 8 stat with the same 2 mana can gain advantage.

Although the stat equal to the total of attack and health of minion. However, the closer  the number of  attack and health, the more efficiency the minion it is. (less waste) For example, we compare 2 same cost minions which are Core Hound with 9 attack and 5 health, with War Golem with 7 attack and 7 health. Both with 7 cost and a total of 14 stat.

However it only cost opponent with a five attack to kill Core Hound such as a tiger. Although Core Hound can deal 9 damage to tiger, however tiger only has 5 health, extra 4 damage is waste.

 
On the other way, your opponent need a tiger and an extra minion with 2 attack to kill war golem. It is a better trade.

The next example, when we compare a warden and a yeti。

If opponent has 3 minions with 3attack. A Warden can only deal a total of 3 damages but Yeti can deal a total damages of 8 and take out 2 opponent minions.

However, class specific minions and legendary minions usually have better stat than normal minion.

For example, if we compare a priest specific minion which is dark cultist and a common minion which is injured blade master. 

Although both have 3 cost and 7 stat , however dark cultist has a deathrattle which is adding 3 health to a friendly minion which contributes about 9 stat or 8 stat because usually you don’t have a minion beside when you play it. But if u have one, your opponent will think twice about which to attack.

For example, legendary card Cairne Bloodhoof  with 6 cost have 9 stat with a deathrattle to summon another 9 stat which approximate 16 stat minion with 6 cost. We usually do not simply sum up the stat together(9+9=18) because it has a chance to be silenced. But compare it to a common 6 cost monsters which is ogre with a stat of 13, it definitely worth a lot.