With the current state of air travel I’d strongly recommend a direct flight. Over the past few years I’ve had no shortage of troubles with luggage and connecting flight issues, and in my last job I traveled a lot.
I’ve flown on both United and Alaska, although I’ve flown on United a lot over the past few years. I just finished an assignment in Germany and was making regular runs between Frankfurt and Dulles or Frankfurt and Chicago on United without issue. Just took a flight to Belize on United as well without issue.
The familiarity with outdoor-related items really has more to do with the specific airport than the airline. I don’t think you can go wrong with either airline, but I’d definitely give preference to the direct flight with all other things being equal.