How long are you thinking you’re going to be living there? If it’s a year or two, you can choose something different than if you’re thinking of something much more long term. Is this a place to stay, or a home? IME, it makes a world of difference.
Personally, I’d always choose a closed off bedroom over a studio, for the privacy if you have guests over and for the more flexible decor options.
How are you about things like doing dishes - for us, a dishwasher was pretty much a must, but that might not be possible where you are.
Laundry in the unit vs in the building vs on the block vs further away. I prefer the first and have never settled for less than in the building. Coin laundry in building, or key access/fee in rent can also come into play.
Water pressure in the shower is something to check; I’ve lived in a place with a nice renovated washroom, but with the merest trickle of water from the shower head. It sucked.
Kitchen counter space: is there enough room to prepare food comfortably, or is there only the tiniest space? Is there room for a microwave/toaster/toaster oven/coffee maker/knife block/spice rack/etc ?
Storage space: Is there room to store your empty moving boxes, your seasonal clothes, sports items, tool box, spare light bulbs, cans of paint, bicycle, etc?
Cleanliness: if the unit is carpeted, are there stains/odours/etc or is the carpet clean? Are the hardwood floors decently smooth, or all splintered? Are tiles in pieces or whole? Things like this can tell you a lot about the landlord and the types of tenants he’s accepted in the past. They aren’t necessarily deal breakers, though, but if the landlord offers to fix something, get it in writing with an agreement that if it isn’t done, you can walk away from the lease if you can!
I don’t recommend taking a unit with a window over the building’s garbage bins. It stinks, and you’ll be woken up by garbage pickup every week!
Good luck! I like apartment hunting when you have time - we were lucky with this place, that we found on our first visit of only one day in the city, but I’ve compromised so much on previous ones!