A ton of our revenue is spent on advertisements. So the 2-3% back we would get from something like Amex has a large effect on our take home, even if it's in the form of travel and stuff.
I had a lot of experience with this in 2014-2016. The spending was in EU/UK but it wasn't with EU/UK based cards though, so I can't help much with directing you to a jurisdiction (aside from mentioning that BoC does issue AMEX cards, I personally never got one from them, so can't say much more).
Something that you didn't mention, though:
What currency and what country are you going to be charging in? It's definitely something to consider, because your 2% could easily be eaten up by currency conversion and foreign transaction fees as well - you'll need to do
due diligence with each card if it's going to be cross borders. (if its cross currency, it's going to be extremely hard to pull off).
Something you may also want to consider if the entity/tax setup will allow it, is using personal cards for charging. I imagine that you'll find a lot more options offering rewards, however, it's possible depending on the volume and the bank issuing the card, that you they may have an issue with the business activity on a personal card.
I imagine (hope) that you're using a CSP of some sort for setting this new entity up....did they have recommendations?