A pair of jeans
I wear a pair of jeans for most of the year, and only owning two pairs keeps things nice and simple. That's one in the wash and one to wear. I used to love Hiut jeans that are made right here in Wales, but after I had to send them in for repairs twice, I started looking for something more durable.
I found that in Swrve cycling jeans. They're super durable and comfortable, as they're made with a cordura blend. I would have preferred something that is 100% cotton, but it turns out cotton just doesn't last that long. Most of my wear and tear happens in the crotch area, as I walk a lot, and the Swrve jeans solve this with a seamless diamond gusset. It's brilliant. Having a higher waist in the back also helps. Two pen pockets and reflective strips on the inside legs are just a bonus.
My first pair is almost two years old now, and the only area that needs to be repaired is a hole in my pocket worn out by my keys. I just received my second pair.