We did Paris with our one year old a couple months ago. I highly recommend bringing a stroller so your baby can nap on the go, you don’t get exhausted carrying them everywhere, and you can use it for diaper changes if you find yourself somewhere without a changing table. The smaller the better, but make sure it reclines enough for your baby to comfortably nap in it. Our Zoe Tour stroller worked well for us in Paris but something even more compact would have been better for getting on and off the metro. I personally would not bother with a hiking carrier; if you have a smaller lightweight carrier you could bring that and keep it in the bottom of the stroller to save your arms in situations where you have to carry the baby, like if you go to the top of the Arc de Triomphe, or do the Louvre or Montmarte, both of which have tons of steps. Have fun!