JR Pass or Hokkaido & Tohoku South Hokkaido Rail Pass combination

I will be flying to New Chitose then spending 21 days in Hokkaido using Hokkaido Pass & rental car then travelling to the northern region of Honshu, namely Aomori, Iwate & Akita regions before flying out of Narita airport.

On Day 5 I will be travelling by train from Sapporo - Wakkanai 11,090 yen. (Then rental car until Day 11 when train travel resumes).

From Day 11 until Day 17 I will be travelling Abashiri/Kushiro/Toyura/Hakodate with unplanned stops along the way (7 day Hokkaido Rail Pass 29,000 yen).

On Day 21 I leave Hakokate and travel south arriving at Narita airport on the afternoon of day 28.

The Tohoku South Hokkaido Rail Pass 37,000 yen is only 6 days (but does take me to Narita airport).
I would have to pay my way on Day 21/22 and start the pass on day 23.

Day 21 Hakodate to Aomori is 8560 yen.
Day 23 Commence Pass - travel to Hachinohe, Akita before arriving at Narita on Day 28.

Do you recommend buying the JR Pass instead of the Regional Passes?