For mixed surface touring, what would be the best tire for mileage?

Maybe a Schwalbe Marathon Plus, but many don't like they way they handle, they're heavy, and they can be difficult to install. I have one pair with 7000 miles on them, and they simply will not die, but I don't like them.

Or if you've got tire clearance, and want a plus tire, the Surly Extra-terrestrial.

I've been happy with my 35 Schwalbe Marathons on my Trek 520. They definitely role better than the Continental Top Contact Tires I was running previously. Just my $.02

Thank you, everyone.
The bike is a 1989 KHS Montana Summit. 26x2 is the widest that will clear the chainstays.

Schwalbe Mondials are a good option.

This is a Kenda Kross (26x1.95), that have road tread down the middle and dirt tread on the sides. I've never ridden Kenda so I can't vouch for them, but the tread design might work for you

I'm using 26" Schwalbe Marathon Plus 2.0 width on my converted mountian bike and they've been great. I run them at the maximum recommended psi when running on pavement and 40psi when on gravel and off pavement. They feel really squirelly on pavement at 40 psi, but fine at max psi. The've been wearing great. The 35 width Schwalbe Marathons on my 700c bike haven't lasted near as long.

For those who struggle mounting wire beaded tires like the Schwalbe Marathon Plus, this video helped me. I can now mount them without tools.

I put a pair of 700x32 Michelin Protek Cross Max tires on my new touring/utility bike.

So far (500 miles), they seem durable, and quite sure footed... good traction wet, mossy, and even a limited amount of ice or slush.

I did, however, find them to seem a little slower than other tires I've used such as 25mm Gator Hardshells.

I'm keeping them on the bike for now, but I tend to pound the miles, so a little speed difference may well be a big deal.

Unless you need the puncture protection, Compass Rat Trap Pass would be a light, high mileage mixed surface tire. It’s 2.3 side, tubeless compatible, which could give you some built in flat protection. There is also a version in 1.8 side if the other one is too wide, also tubeless compatible.

I haven’t used the 26” version, but use the 700x35s on a few bikes that I tour and gravel ride on. I’ve seen other users claim they are getting 4,000 miles out of them. I’ve only put around 500 a set on mine so far, no signs of wear, no flats.