The current competitive meta revolves all around rushing free spirit and chopping in order to jumpstart your economy. Since luxidoor have quite a lot of woods and they can get free spirit fairly quickly they can get going sooner than most. There is even discussion to raise hoodrick up to that same tier due to all their available trees.
If you are interested in Polychamps, you can look up the server in discord. Polychamps revolves around 2v2 and 3v3 competitive games between teams which, in my opinion are probably the best way to really learn the finesses of the game. After all you discuss every move you make and always have a second opinion.
For general 1v1 competitive you can always just go to the main polytopia discord server and do some ranked matches.
Polymasters and the facebook league are another two highly competitive 1v1 leagues.
Imo winrate 90% in random matches is a good time to step into the more competitive leagues.