There are a limited number of players in my area, and the other most available player will only ever play "to the death!!" as a game, which is the most boring of games in my opinion. I need some more convincing arguments to bring them aroound to objectives or really ANYTHING ELSE.
Try challenging them!
I mean, you can say to one of those players
"Ok, we have already battled face to face... but I BET you can't defend that hill (as an example) for 4 turns if your army is 1/3 of mine!".
Or viceversa: "Try to get the treasure in that building I am defending with my Temple Guards before the 5th turn: you can field three times my models count, but if you can't reach it in time I can put in play Lord Kroak".
I would accept immediatly to play a game like this...
Or maybe try to imagine a sort of narrative scenario, like
"In the Realm of Life, a comet has fallen in the middle of a dangerous forest [your battlefield].
Some say that the heavy metal hidden in it is used to forge indestructible armors, others that it's a source of arcane and deadly magic.
What is sure is that any race wants that celestial thing. [so anybody can play his favourite army]
Now, two [or more?] opposite factions fight for the control of that strange object: who will be able to steal it from the hands of his rival, and bring it home without succumbing to the enemy's greed?"
This "battleplan" would consist in a sort of tug of war for the control of the comet:
with some little modifications it might turn into a funny game, enough different from the regular battles to be interesting, but enough similar to regular matches to seem suitable for anybody!
[Don't know if I answered properly your question, but I think there's not some sort of
convincing argument to make someone play in a particular way

]