Standard, setting aside the thread diversion into computer nerddom, while Aeroplan is not as obviously revenue based as MP, as Jack Jia mentioned, the fine print is that the cheapest (Tango) fares on AC earn only 25% on Aeroplan, and lowest United fares earn 50%. So there's a pretty strong form of somewhat coarser revenue dependence.

Unless you have high frequent flyer status, when you redeem a reward flight, at the moment you will usually pay higher fees on Aeroplan than on Mileage Plus. There are some important differences in redemption charts too.

Therefore you could make a detailed comparison on how much the fares you fly will get you where, how long it will take to get enough points for the rewards you want, and how much you will pay, and choose on the basis of that. That's the spreadsheet nerd approach.

An alternative perspective. It sounds like you fly enough to care about where you accumulate points, but not enough to be redeeming that much immediately. Both Aeroplan/Mileage Plus are devaluing their programs whenever they can; sometimes one is "ahead", sometimes the other for a while. It's hard to guess what will happen over the next several years.

You don't mention where you are based. If you are based in Canada, I would go with Aeroplan since it is easier to accumulate non-flight Aeroplan miles in Canada than MP (credit cards, etc.). If you are based in the U.S., I would do the opposite for the same reason. Given your patterns, the best thing you can do to get value out of your flying before Aeroplan and Mileage Plus devalue it away is to load up on additional points somehow, and therefore use points in whichever program before "inflation" eats them up. That's why additional earnings options are probably more important in your situation than the details of flight/fare earnings ratios and redemption costs.

[Editing to add SAP said some of the same just above - I missed I had this thread open for hours while doing something else and didn't update! Sorry!]