Is there a point to your post? Is English your first language? Are you a SPAMMER? BTW - "typical" filters DO NOT soften water - they remove particulate and other microscopic things. Softeners, soften water. They can be combined with a filter if your application warrants. Better find a new job - one that you know something about.

We are in the middle of a renovation/house expansion. Would it make sense to include a water filter? Is it worth getting a whole house water filter or just one that goes under the kitchen sink? We don't have well water, just regular city water in Maryland. I'm leaning towards under the kitchen sink. Any brands one should get or stay away from?

I use a monthly service where they swap out a canister - been using this for many years and very happy. I use one from Rayne (there's local distributors so Google) but I'm sure others like Culligan provide similar services. I pay $32/month. Here's a link to the longer discussion... https://www.houzz.com/discussions/5937025/recommendation-on-whole-house-water-softener#n=51

A reverse osmosis system for whole house would be huge and wasteful. Depending on your needs, many install a whole house filter, and then install point-of-use systems. Reverse osmosis for kitchen use is typical. It depends on your water quality.