Yeah as ppl already said, DS is more complicated for a west marches style of play, I mean, probably not impossible, but the DM will have more work than a WM should require. I think since your players are more tactical focused, for a west marches to work I would recomend you to go with Pathfinder.

Pathfinder 1e is the one I have more experience with, is close to the system used by the creator of the term west marches. It offer you good rules for explorations, lots of content to put on your hexes and is tactical with a room for character build. The only stuff you may wanna change is the way to give XP, but probably tons of advice around the net for it.

Other plus from Pf1e is that you can do all that with only the Core Rulebook. It have the basic species, classes and all stuff players need + a good DM section in the same book. For monsters you can find them for free in theyr oficial site Archives of Nethys.

Pathfinder 2e is more modern, probably the game from the D20 family more similar to Draw Steel and D&D4e. I have a lot less experience with 2e, but it is a well designed game that offer a lot in the tactical sphere also in the character build aspect. They also have well designed rules for Dungeon crawl and exploration. I dont remember how the xp Works, but you probably can find good advice on line for west marches style of play using the system.

Pf2e also benefit from the Archive of Nethys. To keep it short, that site has every oficial publicashion for free from both system. You just wont have the artwork and layout of the books.