I'm commuting now on a rigid 29er with mid-drive. I'm finally wearing out the rear tire, and need to get a replacement, so I'm looking for recommendations.
Bike: Giant Toughroad w/ BBS02 conversion, rack and panniers (60lbs loaded)
Rider weight: 160 lbs
Riding conditions: Mixed road and path. No snow, minimal rain.
Size: 29x2.0-2.2 (would like to stay above 45mm).

Priorities (in order):
1) Traction and ride quality
2) Lower rolling resistance
3) Tubeless
4) Flat protection

My current tires are the stock Maxxis Silkworms, that are acceptable, but they're slow. A good gravel tire could work, but most of those seem to be about 35mm. I would prefer the larger tire just so it's easier for off-roading. Smooth tread is ok, but I think some mild tread may be beneficial for my riding.
I'm currently thinking something like a Continetal Race King or Schwalbe Thunder Burt, what else should I be looking for?