with the indoor units the db ratings differences are so minimal between leading brands its almost insignificant as a deciding option as youre not going to notice a 2-3db difference
Focus on the noise ratings of the outdoor units and the size of the fans operating them, outdoor units are mostly noticed on back to back installations so be wary of where the outdoor unit goes.
the most important ratings (IMO) is the COP rating which is how much heating it produces for the amount of electricity it uses.
A while ago when I was looking into systems to warm our home some of the differences were insane, between 2.5 - 4.5!
We ended up with a mitsi ducted system and an additional panasonic high wall to help assist heating the living/dining/kitchen area both do a great job
Obliviously the better the efficiency the more they cost but if your plan is to be in your home long term then it makes sense to spend the extra
We had a daiken system installed into one of our rental at the beginning of winter and the feedback from our tenants is that its good, quiet and the electricity bill has only gone up slightly which is expected in winter, saves me money from sending a load of firewood around each winter too :-)