I disagree that it has to be Brio! As long as it's a wooden set they are all interchangeable. We have lots and lots and lots - Brio bits are great but they fit just fine with the Ikea, Bigjigs, Lidl etc etc. Yes some are a bit stiff to put together or take apart but it's not a big deal, and the more you play with it the more those bits wear down and they get easier to use.
The thing we always seem to lack is long straight pieces. And we have an abundance of trees which never get played with.
Anything with moving parts is liable to get loose over the years - we have a level crossing with barrier which just falls down now (mind you I bought it for DS1 who is 16 so it must have been going a while) and the Metro tunnel DS2 begged for for Christmas is utterly shoddy and the cogs inside it shatter. Brio will only replace it if I box up the entire set and post it to them so DH is going to try and 3D print a replacement I found a pattern for on the internet.
The Lidl sets they do around Christmas time are absolutely brilliant - the Metro station they do is better than the official Brio one, and their main train station is fabulous but we have shattered the roof about 3 times by accidentally standing on it.