I find the Canon Game to be the easiest for me. I can compensate for wind fairly well and get some good shots in. Altho, it really doesnt seem to matter how good you are, as long as you hit the target all 4 times. I can get quad bullseyes and 4 non bulls and still get the same amount of experience points; 4.
I like grumpy gobblers. But if you would have alot of high end snacks the dance game is the fastest way to level up because you can just fail and feed.
I would suggest the dance game, since it's quick, and if you have good memory.(listen to the music and that may help you)
If you want to take more time and have a higher chance of getting good xp for your pet, then try the maze game, which is easy but slow. I would only suggest the maze game if you have lots of time.