Albuquerque and Tucson are about 318 miles apart by road. Split the difference and you arrive near El Paso, the city closest to the halfway point between them. That puts roughly 4 hr 49 min of driving on the Albuquerque side and 5 hr 33 min on the Tucson side — the fairest single meeting point among the cities near the middle.
That's a half-day drive from each side, so El Paso suits an overnight or a weekend rather than a quick coffee — long enough to want a reason to stay, short enough to drive.
If El Paso doesn't have what you're after, Phoenix and Las Vegas are also close to the midpoint and worth a look — each keeps the drive reasonably balanced between Albuquerque and Tucson.
City descriptions adapted from Wikipedia (CC BY-SA); photos via Wikimedia Commons, credited above.