Our current dryer vent exhaust is on the roof, north side of the house. The piping has 1-90^ bend and 2-45^ bends from what I am able to see. The RED marks the existing line and the magenta is where I am considering stubbing it out the wall. Existing run is about 12-15 feet long. We have had some issues with lint build up, but typically it is right behind the dryer. We are getting a new roof, insurance paid for, and want to make sure this is vented correctly...keep the roof vent or vent directly thru the brick veneer on the porch?

If you can make that change fairly easily I'd do it. Much safer from a potential fire standpoint.

Agree. Shortest run and as few turns as possible would be the ideal.

I am a certified dryer vent tech through the CSIA. Your current dryer vent does meet code barely. Code is galvanized pipe is all enclosed spaces maximum of 25' subtracting 5' for each 90 degree turn and 2.5' for all other angles.

The issue I believe you are dealing with is the long vertical run. I have never seen one work efficiently even when run to code and under 10'.
I would recommend drilling a 4.5" hole through the brick and running your pipe out to the front porch. It will increase the efficiency and lifespan of your dryer and reduce lint buildup.
Any questions my email is in my profile.

git'er done,
I had a similar situation 2 years ago.

because of a couple of people here I alleviated 3) 90 degree turns and 5 feet of pipe.

you could hear the dryer vent sound different ,
probably gave the dryer an extra few years

Good mod, do it!

Only 2 small drawbacks.
1) Might get some Lint, steam, noise on the front porch.
2) Stray animal attractant. (attracted to the warmth in winter)

My mom had a duck spend the winter under her dryer vent! It left when the weather broke.

Feed duck corn. Duck gets fat and tasty. Holiday dinner gets less expensive and tastier.