I generally collect Esso extra points, rather than Aeroplan miles. For those with an RBC Avion card, the points can be converted to RBC rewards which can be converted to BA miles. As an example, if you put $45 of premium gas, you get triple points, so 135 points. This can be converted to 81 RBC points (note you need 2500 Esso points to be able to convert to 1500 Esso points).

The 81 RBC points can be converted to 120 BA miles under the current 1.5x promo with RBC/BA. If I charge this on my Avion card, I get an addtional 45 points which converts to 68 BA miles so a total of 188 BA miles for a $45 gas purchase.

Even if I just purchase regular gas, the $45 purchase works out to 108 BA miles.