If all are tamil. I am as local as possible. Filter kaapi in filter kaapi style. mix guess, go for glass , china ware. most of the times T, ginger T.
My DH is a coffee geek. He has had the same Italian espresso machine and matching grinder for the past 25 years. It’s not as fancy as the one-touch machines but it makes great coffee and also froths milk so it’s easy to whip up whatever guests want.
It depends on the guests For elders i believe tumbler and dabara i have given like that before and they relished it. For young people cups would be comfortable. I used to sense how they are. It may reflect on how they talk, and their age too. Based on that i will give. But my mistake - i wont ask them whether they are comfortable with cups.or tumbler.
Our guests are usually fine making coffee the way they want. we don't usually have any guest who is too formal to be served . As a North Indian, I have absolutely no idea how to drink from a stainless steel tumbler (I learned from this thread that it's called Dawara). We use either coffee mugs (for drip or French press) or espresso cups.