I'll try and think of general flavors that you'll likely find. In NorCal we are spoiled by so many choices and a lot of shops have their own unique blends.
Milk teas:
jasmine milk tea: I like the mild herby flavor
brown sugar milk tea: My husband's favorite. He loves his brown sugar. A bit sweet for me, but I can handle it if diluted with water or tea at home.
black tea with salted cheese/creama on top: the salt adds a nice depth to it. Usually you sip these instead of going straight in with a straw, but eventually the cream mixes with the tea.
Tea teas:
mango green tea: I'm a sucker for anything with mango in it! (so if you have an option for a mango milk tea, definitely try that too!)
strawberry tea: bonus points if it comes with bits of strawberry in the drink!
any combo of fruits that I like-tea
Toppings: (they can be combo-ed with any sort of tea, but I have my preference whether to pair them with milk teas or tea teas)
honey boba (for milk or tea): can be a hit or miss for me, some shops don't serve it soft enough for my taste so I usually opt for one of the following toppings.
grass jelly (for milk): very light herby flavor. I like sucking up the jelly through the straw.
egg pudding (for milk): it's got a yummy custard flavor. I like it with jasmine tea in particular as it balances out the herbiness of jasmine.
mango crystal boba (for tea): Not to be confused with mango popping boba, I like this for it's texture and taste. Not every place has it so I always get it if I see it.
fruit jelly (for tea): Comes in many flavors (and shapes sometimes), I like the texture it adds to tea teas.
basil seeds (for tea): I LOVE the texture and chewing these little things.