Looking for opinions on those with experience with Deco or Orbi (& 2Degrees)

I'm in the process of transitioning parents from copper to fibre. Old ISP have told them they have to return their (outdated) modem, so I'm looking for something to replace that - preferably 2nd hand. Main contenders are a Deco vs Orbi.

My home system is setup with Omada system which is very solid, so I have familiarity and faith with TPLink, whereas Deco is probably equally as good and they may find the ISP (2degrees) is likely more supportive with Orbi as I understand that is what they provide normally?

Connection is 100/20, so anything Wifi5 or better would do the job. The house is fairly large hence looking at a "meshable" system. I have seen online people complain about the Orbi systems needing to be frequently reset.

Their house is quite large, however they aren't too worried about getting range at the far end of the house (bedrooms) - mostly in the living areas. Main challenge will be getting range out to the garage/sleepout area which is about 20m away from the house, but that can be via powerlines if the mesh system can't do the job.

Other considerations - (budget, don't want to spend much), support (that would be probably me, so the more reliable it is the better), That's about it.

I'm hoping these systems can be configured with their old SSID name and password so all their devices will instantly connect to the new system.

It seems to me that a lot of people selling this gear on Trademe are asking in some cases for near new retail for outdated gear - which in a lot of cases they probably got for free from their ISPs anyway!!

One other option would be Fritz!Box which I also am familiar with so will be easy to setup.