Tankless or instant is when you want ease of use and no hacking.  It is not ideal for long duration high volume flow esp rain shower but can still work. Built-in pump is optional for condo (usually not necessary) but mandatory for top floor landed.

Tank storage hot water is when two or more bath outlets require centralised hot water. Assumes hot water plumbing already installed otherwise need to hack. Centralised is natural stepping stone to installing other centralised hot water systems like solar hot water or gas as the central hot water plumbing distribution is already there. Here the centralised tank will be relegated to backup heater on continuous rainy days. Pump is required for all top floor bathrooms or where pressure is weak.