The On the My Side and the Fendi Peekaboo are very different purses with different functions, IMO. The On My Side is tote like, where as the Peekaboo is a smaller, sleeker shoulder bag with a smaller capacity. I bought and returned an OMS because it was too heavy for me. When I carry a tote, it's because I'm going to need more stuff that day including a water bottle. By the time I got it packed, not stuffed, it was heavy and uncomfortable. I love the bag, it's just not for me.
I did buy the Peekaboo lite and I love it. It is one of my most luxurious feeling handbags. The quality is very apparent and the leather is like butter. It also has a higher price tag than the OMS.
I would for sure buy an OMS if LV made one in canvas. Hope this helps.