Heavy Weight Pants

I have 2 pairs of the TLD Sprint pant and I'm really happy with those.  I picked them up when the designs/colors change and they mark them down pretty cheap.

Chromag feint 

Looks like eBay still has some Dakine Thrillium Heavyweight pants 

NF DP5. Not crazy heavy but durable af

NO ONE MAKES GOOD DURABLE GEAR ANYMORE!! buy og tld on ebay

I have TLD pants since the mid 2000's and like the brand a lot. However, durability isn't everything, as the rubber pieces on, say, the iconic GP's that Sam Hill was wearing anno '08 aren't as comfy by today's standards and they lack pockets. My go-to pant in the last 2 years were TLD Skylines and I also like the Ruckus Cargo quite a bit, although the cordura-style material was less resistant to tire marks than I thought. OG Sprints are also very very good.

Mx

Where are you looking for durability? Different options for different needs. You can go lighter and still have great durability, but there's always a tradeoff between ultimate abrasion resistance and weight/comfort/heat. I designed Abit Gear pants for everything below except the heavy fabric.  NF has good options if you want the pants equivalent of DH tires. 

Things that make long-lasting pants/shorts: 
-Waist adjuster (velcro clogging or wearing out): Get something that doesn't use velcro.
- Stitching and zips (most common failure): Find pants with YKK Zips and heavier nylon thread. Key stitches at the back need to be a stretch stitch vs standard top stitch.
- Keys/tools blowing out pocket bags: Something with bottom-of-pocket reinforcement.
- Fabric that survives a gnarly slide on rock: Heavy weight nylon fabric is your friend.

Choose nylon with 5-10% elastane/spandex for stretch. Avoid polyester pants. Nylon is 30% stronger at the same weight without the stiffness of poly and nylon is stank resistant. Poly dries faster, takes sublimation prints, doesn't expand when wet, and is cheaper - pros and cons to everything. Most pants from quality brands will be Nylon.

Fly f16 pants 

Fabric weight is your friend in this case. Get the heaviest nylon that you find tolerable. Many manufacturers like me don't list fabric weight since no one knows what it means. Fabric weight is spec'd in GSM (grams per square meter). 

My pants are 160 GSM nylon with 8% spandex. I'd call these "medium light weight". This is as light as I could go, balancing durability and decent breathability for my personal preference. I get to design what I personally like

Abit Gear shorts are a little heavier, and they can definitely take a hit. These are 190 GSM nylon with 10% spandex - I'd call them "medium weight".  Shorts have lots of airflow allowing a little more fabric weight fudge room. That said, I wouldn't wear my own shorts in a hot/humid climate like Houston. I'd go ultra-light polyester in that climate.

Balancing heat vs durability is always the trick, so I designed thigh pockets to double as vents on both pants and shorts. Pockets require zips and a lot of stitching = a lot of labor, so the downside to this design is higher cost - especially when stepping up the thread spec.

If you're looking for exceptional abrasion resistance, find something over 200 GSM nylon. I just looked at NF and they changed up their product line since I tried them a few years ago. Their DP4 pants were stout.

NF all day babyyyyy

Iv been running the Signature Rover pants through winter here in NZ. Picked up multiple pairs when onsite. Have been using for riding, trail work, just every day work pants. Have been really good so far. Are a heavier weight to the TLD skyline pants i normally ride in.