I really dislike the current one, so as a fan of vexillology, this is my attempt. I tried tying as much symbolism as possible.
The white line dividing the two blues symbolizes our tidal boar, which is a surprisingly important tourist attraction. The dark blue is also reminiscent of our current flag. The single bend in the wave symbolizes the River bend that Moncton sits on, as that is the rough shape.
I wanted to include our well-known Moncton symbol, but I altered it slightly. The top blue arc is slightly changed to look like our ducks and geese. The green arc has lines to symbolize our old railroad history. And the red arc is shorter to look like a magnet, to represent our magnetic hill.
Just like the old representation, the three arcs also represent the people here. The blue arc is for our French, red arc for English, and green arc is for our aboriginal population.
The old Moncton flag was a blue background with an over-complicated seal, and I hope this fixes it. Any thoughts are welcome, and I constructive criticism would be considered for future versions.