We have a study group for Tobira here in the forum if you want to jump in! Currently working on chapter 9 Tobira study group - #95 by Marifly
I’m working on Sou Matome for N4. Just finished the N5 book and started the N4 book. I think you’ll learn more from Tobira, while Sou Matome is more directed towards the test. I think finishing Tobira and then switching to Sou Matome is a great plan.