+1 for the request, though I am skeptical you can find good ones. I am subscribed to PMHQ blog. I mostly find it to be corporate people writing great things about their own products. Nothing mostly which talks of rubber meets road kind of stuff. I would gladly read two kinds of product blogs 1) Failure post mortems. 2) Things which explain a startups decisions step by step. Eg: Why did Uber choose marketplace model instead of a fleet, how did zapier decide to pick a specific niche while starting off, etc