I don’t necessarily think you NEED an infant carrier, but they are SO great to have for multiple reasons: bonding time, your ability to get things done in multiple rooms without having to pick baby up and move them, and being able to do everyday chores hands free.
Bottom line, the ERGObaby wins for overall comfort and ease of use. And I would pick the 360 for its versatility for baby as they grow.
This carrier is more expensive, but in this case, you get what you pay for. The Infantino is not as soft or sturdy. The Moby Wraps are super soft but super hard to do alone, especially in public if you’re short. How do you keep the thing from touching the dirty ground?! The Baby Bjorn was so easy to use but has no lumbar support and therefore, my back was killing me after about 30 minutes. There are many other options out there, but this is one situation where I would argue for the more expensive ERGObaby 360.