If you want to be close to the action, I’d suggest looking at Podil or near Khreshchatyk. I usually check the Visit Kyiv site when I'm booking because they have a really solid list of vetted places here:
https://visitkyiv.com/accommodations/hotels/. From my experience, it’s worth picking a hotel with a good breakfast included—it saves so much time in the morning! I stayed at a boutique spot near the Golden Gate last time and the atmosphere was just incredible.