Town Hall 9 is one of the most important THs to know what to do first on. If not you could end up looking really bad, not to mention being able to be beat really easily. You should have at least 3 builders, if not I would recommend starting over your game.
3 builders: Obviously, the best part about Town Hall 9 is the X-Bows. So, I would say getting one, if not two right off the bat is smart to do. With your other builder(s), start upgrading all your new walls to at least 7 and getting all your new buildings even in level with your old ones. The lab upgrade may look promising but level 6 troops are expensive, so you won’t be getting many right off the bat.
4 builders: With 4 builders, you should definitely be getting 2 X-Bows! Since you have one extra builder, I would work on your drills. Build the new one and get them both to level 6. With your last builder, once again, work on all your new stuff and getting it up to par.
5 builders: This is where it gets interesting. Since there are so many new things and you have so many builders, you have many options. I will list the 5 most important upgrades you should do. These can vary depending on how many resources you have. Do what YOU think you need most.
1. Building/upgrading any new buildings.
2. Building 2 X-Bows
3. Building/upgrading your DE Drills
4. Upgrading your labratory
5. Building an Archer Queen.
Note: Do not upgrade your Town Hall until you have completely maxed your base!