If you have a 150 litre tank, I would buy a canister filter.
Oversize the filter for goldfish, as they are messy fish to keep and need extra filtration for water to be healthy and clean.
Normally hang on back (HOB) filters are used for 100 litres and less. Its up to you though. They will both work fine for 150 litre, but canister will work better in my opinion. If you choose HOB, go for 10x the water flow per hour of your tank size. (150 litre tank will need around 1500 litres flow per hour) Canister can be around 5x the flow.
HOB filters are cheaper, and use less electricity power than canister, and also offer easier access. The most popular brand for HOB filters is Aquaclear. And for your size tank I would buy the largest size, which is Aquaclear 110.
For canister filter, which does a better job at filtration in my opinion, my favourite brand is Eheim, but they can be pricey.
Something like this if its in your price range:
EHEIM professionel 3 600
If you want something cheaper, and still stick with eheim, then something like this:
EHEIM classic 150L
P.S.
I have aquaclear 70 on my 103 litre tank, and my water is crystal clear. Have a look at my profile pics to see.