If I'm in a hurry (I don't mean in-game... I mean if I only have a limited time to play, and I've got a goal I want to accomplish before I shut it down, like gather/deliver the items I've been sent to gather), I try to avoid combat... Though if I'm being pursued for too long, I'll often turn around to punish them for their audacity...lol
There have also been a few times when I'll see a Vaegir party getting beaten up by a larger enemy party, and I'll try to wait around until the fight is over, and the Vaegirs have been captured by said enemy party... Of course, I then wipe that party out to claim my new troops (I'd do the "right" thing and go in sooner, but I can't recruit them that way!)... During this time, though, other wandering parties pick up my scent and come calling... I've run circles around the battle I'm watching to keep out of these fights, and allow the clock to run (though if I get annoyed at running around, I'll take out the followers so I can go back to sitting there with the spacebar held down)
I also tend to avoid Dark Hunter parties, as these usually inflict the most casualties... Even though I've now got a nice large stockpile of extra troops at Radoghir that I could burn through, I still don't like losing anyone... I will attack these guys (or allow them to catch me), however, if it will bring me something worth it (if the Dark Hunters are carrying some good prisoners, I'll take them out to absorb the rescued units, which sometimes end up just being replacements for the ones that I lose in battle...lol)
As Amman d' Stazia said, I also allow the Swadian Deserters to roam free for a while, in hope that they'll do some damage to one of the larger parties to soften them up for me ("The enemy of my enemy is my friend", after all, even if they don't seem to agree...lol)
I'm not too keen on facing the 300+ Swadian Patrols and War Parties, either... I've taken a couple of them down, because they were holding too many good prisoners to ignore (it's how I got my little cadre of Dark Knights), but it just takes way too long with my current battle settings (up to the default maximum of 40, as I haven't used the battlesize changer yet), so I've been putting them off for gaming sessions that I can spend that kind of time (or when I finally get around to getting the battlesize pumped up)...
The main point of the game for me is battle, though, so I do get into fights quite often... So in all other cases (guess it might seem like there's no other cases left...lol), if a party comes after me (whomever they are), they get to meet the pointy end of my blade...
Of course, I'm now at the point in the game where pretty much the only thing left is for me to go clean up the countryside, so the parties that I usually ignore/avoid are going on my List... Look out Swadian Patrols! There's a 450+ Vaegir War Party roaming around, too, so if I ever feel like being a turncoat, I've got a challenge...lol