I have tanks in every room of my house except the kitchen. The reason I don't have one there is because cooking fumes are not healthy for the fish. Of course you should take into consideration temperature variation, noise and sunlight but also consider where you'll get the most enjoyment from your tank. I recommend the living room or bedroom. My fish do not seem bothered by occasional loud music, do not place them near the speaker. Do not put the tank in direct sun. Kudos to you for doing extra research.

Welcome to the forum!  I personally don't like to keep my fish tank near or on carpet because i'm afraid that if I spill, the water will be all over my carpet.  Right now, I have my fish tank in my dining room because my original area in my living room didn't have have enough space above it for the lid to move up and down fully. As for health, I don't think it's a good idea to keep a fish tank next to a toilet, who knows what's floating in the particles after you flush? I read you're not supposed to keep the aquarium next to drafts or an air conditioner/heater because of the temperature conditions(?).

Our last tank was in the kitchen but as said above light is not good for fish, and we have like windows running along the back wall of the kitchen that are directly at the sun. I am thinking of either the kitchen or my room??

I have my fish tank in my room as I'm a Uni student and it was rather annoying at first but now I like it and its quite soothing in a way! 
I agree with you Vicky! 

Yeah I currently have two tanks in my room as my snails have been in my quarantine tank whilst I treated the maiming for White spot!

I install the output at the water line intentionally to increase surface agitation.

Lol cdale. Not too large just completely taken over, two 55 and one 30.

I like to have my fish where I can see them So I have my tank close to the couch/armchair, and I enjoy listening to the sounds the tank makes in the night too. But I don't really enjoy the fish splashing the water around making even more noise xD

Welcome to the forum.
May I first ask what sized tank you intend to house the common goldfish in?
Common goldfish are much better suited in ponds, than aquariums. Juveniles are okay in aquariums, but I wouldn't keep one there for all it's life, considering that common's can and will grow to at least 10 inches.
So I would suggest buying another variety of goldfish, unless you intend to upgrade the tank to a very large one (around 6 foot) or build a pond (a minimum of 1000 litres is best).

That being said, I am currently keeping a juvenile common goldfish (she is roughly 3 inches at the moment) in a tank in my room But I am intending to find her a pond when she is slightly bigger (around 5/6 inches), the tank she is now, is 3 foot long and holds around 90 litres.
My external filter is silent, the only noise I really hear is the air pump. The tank is situated near a window, I have the curtains slightly open during the day (being white they let a lot of light in anyway), so the tank does get some sunlight but not very much direct sunlight.