This completely depends on the usage of the geyser. If you want to use the geyser for household activities, then we suggest you buy an instant geyser. Because the instant geyser has a smaller capacity which is sufficient for household activities but not only that, it can heat water much faster which means you can get hot water instantly, as the name suggests. But if you want to use the geyser for bathroom, i.e. for bathing then we suggest you take the high capacity one like the 10L, 15L+ ones depending on the number of people who will use it at a time. This is because even though it cannot provide fast heating but once heated it can provide water for everyone and it can also keep the water hot for a longer period compared to instant heater because of its smaller capacity.