Best System for a West Marches Game?

[S'mon]

You provide the Inherent bonuses only as rewards for area completions. Like magic items, which are always a great incentive, mind you, but without doing the parcel system, not always what the players 'use' so much or want, with inherent bonuses, when you grant them, you can give the player a say in the direction of the bonus their weapon/armor gains. This way, the player has some of the feeling of usefulness that was established by the parcel system (the whole 'wish list' but it goes into their pre-existing primary weapon, or armor. Even without giving them a 'choice on how the weapon/armor 'grows' you can still focus the growth according to how it is earned. A group of adventurers who have been fighting to clear out an orcish stronghold reaches the point where you grant an inherent bonus to one or more of their weapons, and you decide to grant +1/+2 vs Orc-kin as a benefit (which is thematic to what they were fighting when they earn the inherent bonus, and encourages them to go out and diversify what kind of challenges they face, to make their weapon more versatile, but also makes the weapon more useful in the current encounter zone(s) as it becomes not only stronger, but stronger still against the current primary foes)

Yes, you can do this with found magic items, it's true, but intelligent foes, especially Vampires and Liches, and Elder Dragons, are actually not likely to keep around magic items specifically geared to fighting their own kind....powerful enough beings would either destroy non-artifact level items of this nature, or hide such things away in other plains of existence. Now, such items do make for grand final chapter/quest-level treasure (we know we're going after a LichKing, we need to go to the Stronghold of the Elder Black Dragon, who is said to guard a LichSlayer)

Use a mix of inherent bonuses, and targeted magic items of lore to incentivize your explorers motivations.

So I think the idea here is that the GM gives bonuses (Boons, in 4e/5e speak) to PCs (Inherent Bonuses) or to their gear (Item Bonuses) depending on what is fought, not what treasure is found.
Yes, that works well.

 

[Clyde Starr]

Yes, exactly...it builds into the story and adds more roleplay to what is essentually a mostly hack'n'slash kind of sandbox game. By building the inherent bonuses into what caused them to happen, you build a living legend out of their weapons, and their heros themselves. Then later on, groups come into the game and hear the legends of the heroes and hope to maybe find some of those lost weapons and armor that they've heard tell about. Inherent bonus weapons of previous games become your artifacts for later games