My take on rules-lawyering vs. roleplaying: there’s not necessarily a divide between them.
If I’m playing yer average D&D adventurer, I’m playing a professional soldier of fortune. My understanding of real world SoF is that they tend to be gearheads: they know the specifications of their weaponry, the reach of their communication systems, several effective tactical approaches, and so on. THeir lives depend on making optimal choices.
So if I’m playing a druid who wants to cast giant vermin, of course I’m going to make a knowledge (nature) check to know which insect has the most potent venom, and I’ll choose a hornet over a honeybee every day.
Now, as a player, I’ve got tools to simulate my character’s knowledge. My character knows a lot about different species of insects, the effects of their venoms on their prey, etc. All I the player know are save DCs and damage dice. My choosing the vermin with the highest save DC/damage dice is how I simulate my character choosing the insect with the most potent venom, based on observations of caterpillar paralysis or whatever.
In general, I come up with a character idea first: a lonely dwarf, exiled from the mines because of his beliefs about the living heartbeat of the earth and his druidic proclivities? A smartass bird-spirit bard? A mousy stubborn girl who despises pretention, is cripplingly shy, and is a deadshot with a longbow? A scarred and profoundly cynical half-orc cleric of a trickster god? I come up with the concept with one eye on mechanics, because I want the character to have fun effects during the inevitable combats; but the other eye is on an interesting concept, and I try to find the mechanics that will make the concept effective.
But once I have the concept, I make choices about equipment, spells, feats, and tactics as though the character is desperate to stay alive. The character is unlikely to make a lousy choice, and I try not to, either.
And then I try to roleplay in a way that’s fun for people: the druid grumbles and has affairs with wolves, the bard spins elaborate stories to precede suggestions, the fidgety archer goes and does something whenever the scene is bogging down in too much talking, the trickster cleric bullshits everybody in a genial/cynical fashion.
The roleplaying and the rules-lawyering can complement one another, if done correctly.