Yeah, it sounds like a strange question, but it's important many times. If not, I probably wouldn't have written this article.
Lets start. The question is, as the title says, whether we want to go back and forth with a single airline, or whether we prefer to go with one and go back with someone else. Again, the answer is not clear, but there are many things that can be said to guide you a little.
One might find a good price with an airline to go, but to come back, you might think the price will be quite high, the qualification will be a lower fee. It may, but rarely. If the fees are high on the day you return with your outgoing airline, it probably means that today competence will also have high fees. The market is the same and it would be strange that two airlines, which cover the same route on the same day, have different demands, because a high fare is due to high demand, right?
Now you have accepted, I will say that this is not always the case, and the exception comes when talking about terrible timing flights. I say to them like this because it really is. Since your flight departs at 7:00 in the morning, you need to get off at 03:00 in order to go to the airport at 05:00 in the morning. Well, of course, if your competence doesn't fly at the same time, you found a good flight ticket here!
There is also a general rule that applies. Whichever route you choose, hot deals will almost always be for round trips, not for single trips. This disturbs you if you manage to find a good offer with another airline. Flying with one and coming back with the other, I can't bargain but also the price is extremely low to come back with this other airline! It's not easy, but if an airline has a good list of discounted round-trip deals, you can almost be sure that the best option is these deals.
At the same time, flying with a single airline will allow you to accumulate miles if you participate in one of your frequent flyer programs. If you go with one and return to the other, you will always earn points with all airlines, but none can be used for anything, since the amount will not be high enough. In any case, real alliances allow you to change some points from here, so you should consider this option as well.
After all, I would normally say that with the same airline you will find the best deal that flies from any angle, and I recommend that you fly with someone else only if the travel conditions offer you clear advantages. In this case, remember that you compromise the shafts at a slightly better price, so think deeply before making the decision.