How to go about fixing a holey laundry room

When I removed some old elevated cabinetry in my laundry room, I discovered two holes in the wall. The first I documented here,

How do I close and seal an old external vent?

and the second can be viewed here:

My dryer in my single floor home currently vents downward through another (third) gnarly hole in the wall:

It continues down a couple feet into my crawl space, and then horizontally out through a wall vent by my deck:

None of these holes were put there by me. 🙂

I was going to try to address this by:

1. Covering the old vent (hole #2),
2. Fixing the current gnarly hole (#3) in the laundry room wall where the flex tube goes through, or patching it entirely and making a new hole closer to where
   the dryer will be,
3. Replacing the extra long flex tube in my crawl space with insulated rigid pipe.

I'm considering, however, reusing the older vent pipe in #2 which goes up the wall, straight through the attic, and out the roof. I wouldn't have to run any new pipe and I could just patch the current gnarly hole (#3) with drywall.

This seems to have some drawbacks as I can't see how lint won't just settle at the bottom of the vertical pipe and clog it. Going down and out instead seems like it would give lint the chance to settle along a greater space and get cleaned out by me later. I suppose this is true only if the rigid pipe can be install co
mpletely horizontally or at a downward angle to the outside.

The advantages of using the vertical pipe would be that I don't have to run any new rigid pipe and this hole is actually closer to where my stacked dryer will be.

Should I reuse the vertical pipe via hole #2 or close it and fix and use hole #3? If the latter, what is the proper way of closing #2? I'm thinking I should shove some steel wool in the opening, pull out the short horizontal tube and fix up the wall.