If you had enough money for Lagstro's idea, which is unlikely, I feel that would be the best one. However:
Where would it be located?
What about visas for Russian and Turkish players? Lots of esports organisations have this particular problem.
What if your players can't attend due to work or school?
How many people can you possibly bring per team in order to make the cost reasonable?
Financing a LAN would cost at least 5k to 10k (or more) just in flight tickets alone.
So Lagstro's next recommendation is clearly the best.