OK First off,
The tank is too small for goldfish (so thats why you should exclude them from your decision making)
Secondly though (just so everyone is clear) Goldfish are not cold water fish, they are definately temporate, but with a very broad range (and a broad range within that curve that they can happily breed in succesfully) - a quick search of previous threads/google etc. can confirm this.
So, if the tank were larger, temperature would not be an issue.
However - Goldfish are messy, greedy and somewhat too physical for gouramis to handle. They would also present fairly docile targets for the attentions of tiger barbs.
A second point is the environmental (not just temperature) needs of the fish. You would need well oxygenated water with a reasonable flow for goldfish, while gouramis need a much more tranquil environment. Both gouramis and tiger barbs prefer plant cover, while goldfish will likely eat/up root live plants (and even plastic plants).
Simply put then, without too much criticism, you need to take your time and research not just the individual needs of the fish, but also, their likely interaction/housing needs - do they clash or do they fit?
Perhaps take a step back and think, what is it I really want to achieve with my aquariums?
That is all.