Help on a new tank

[Era101]

Heater size is calculated based on water volume and how much cooler the room is than your target temp. For a 20G tank you only need a 50W heater as long as your room is usually less than 5 degrees (C) cooler than you want the tank. My guess is this will be the case for most of the year. 75W is needed if your room is usually up to 10 degrees cooler than the tank.

I doubt that my tank is 10 degrees (Fahrenheit or celsius) lower than my room but I'll go for the safe option of 75 watt. My local store has a choice of glass and stainless steel for the heater. My first instinct says to go for the stainless steel for better conductivity and all round stronger materials but I'd like to get some opinions and/or experiences.