I bought my first pair 3 years ago and now I have a second pair of the 3/4 pants for the warmer weather but still essentially having the knee pads. These pants are awesome. Lots of places to part stuff in easy reach, I can fit my smaller bins from my Dewalt screw kit right into the flopy front pockets and best of all, the built in knee pads.
Those knee pads have really saved me these past few months. Been doing an excessive amount of work on my knees and I don't think I'd be able to walk by now without those knee pads being there and I'm not a guy with a history of knee problems either. I always hated the strap on kinds. With these, you don't even know they are there. A pure pleasure!
I have never heard of anybody getting a pair of Blakladers, and while I've never tried Carharts before myself, I've read plenty of people who go to Balklader and never go back.
Disclaimer, (because I may be sounding like a shill at this point but in reality I just love them so much), no affiliation with Blaklader other than being a very very happy and satisfied DIY user.