Which size and which shape
Reckon on at least 40 cl. A mai tai itself is about twelve centilitres of liquid, but crushed ice takes up the rest of the room and you want space at the top for mint, a slice of lime and a straw. In a 30 cl glass the garnish sits crooked and the ice melts too fast.
After that you choose on character. A heavy cocktail glass or 45 cl tumbler shows off the colour of the drink and suits any bar, including when you pour the rest of the menu from it. A tiki mug in ceramic or worked glass hides the contents instead and turns it into theatre, which was exactly the intention when this drink was created in 1944. The hurricane sits in between: tall, curved and built on a foot, which keeps it stable while still catching the eye.
Watch the wall thickness as well. Crushed ice knocks hard against glass and a thin rim does not survive that long on a busy bar.