The J. Press are more trim, and they have only five belt loops. Lately I like Andover Shop a lot, and if you are okay with pleats, they are on sale.

 

I got a pair of dark brown corduroys from O'Connell's to try them out and corduroy is not my thing. Did not like the feel of them at all. I personally vastly prefer moleskin as it's way more soft and comfortable.
I will say the O'Connell's pants are well made and use Brisbane Moss corduroy which is supposedly a high quality fabric. If you're interested and have a Size 38 waist, I currently have them on sale over on the Trad Thrift Store Exchange for half of the price I paid for them.
O'Connell's Dark Chocolate Brown Corduroy...

 

I just bought my first pair of J Press corduroy's this year (I've never tried O'Connell's) and I would describe them as true to size in the waist, high rise, trim in the hips and moderately trim in the legs. The material and construction are great. They come unhemmed but the store will hem them for free.

 

How are the pockets? I feel like that's the one thing that might sway me to O'Connell's. I love good (deep/sturdy) pocket bags, and the pockets in the O'Connell's khakis I have are very nice indeed. But I have never had any Press pants so maybe theirs are just as good.

 

The pockets are decent...adequate depth, good material...nothing out of the ordinary though.

 

Whilst I do not own any cords from Press or OC. I do own many, many pairs of trousers from both shops. I feel OC edges out Press. Particularly in the pockets. OC are just more robust. Press can be had sometimes significantly cheaper when on sale.

 

I can’t compare as I don’t own a pair of J Press cords. The OC cords I have are nice. Well made, roomy and soft. Pockets are nice and deep. One thing about OC is you can pick the rise (short, regular, high) to fit you. I’ve gone OC for most of my trousers as the fit works for me. I visited Press in NYC and the trousers I tried didn’t fit me well. I can say I’ve been happy with almost everything I’ve bought from J Press. If you have a store close, I’d start there. If the trousers fit and you like them, I wouldn’t worry about the potential better quality at OC. If they don’t work, then order OC. They will hem for free, too, but I’d recommend not doing so on the first pair in case you don’t like them, you can return them.

 

Sorry, I am unable to comment directly. I do have experience with Canada, when Brooks sourced top of the line cords from Canada. They were the best corduroys I've ever owned, have a pair made in Italy now made from sea island cotton, similar. The textile industry in Quebec is first class and recall, O'Connell's is in Buffalo which is adjacent to Ontario across the Niagara.