I had some danios in there with him a while back, and he may have calmed down, but i didnt really know much back then, and now that i think about it, it may have not even been the gourami that was the reason they died they may have just died because of poor water quality or other things. also had another gourami in there but i know that equals aggression
IME, it's hard to deal with aggressive fish (I had an aggressive DG).
The problems tend to arise when the aggressive one is introduced first, it will setup its territory, sometimes the whole tank! Unfortunately there is no way of identifying the aggressive ones in the shop.
One thing that can help, is to remove the aggressive one (much easier with a q-tank), re-arrange the tank and/or add new decorations, and allow things to settle overnight, then re-introduce the aggressive one. [This should be a last resort, but it can help]
[Note: if you don't have a q-tank, this won't work]
As for what tankmates, I would go for fish that inhabit different areas, so for example if your gourami is a mid-top dweller (which I think most are), then I'd go for a species that is more bottom-mid dwelling (e.g. give the kids two separate sandboxes to play in), thus they won't be in each other's territory too much.
Also, a floating plant for a gourami could help, as it gives it somewhere to chill out in the dark at the top of the tank, without having to try and find peace in the decorations down lower etc.
That's my 2c anyway
Oh, and re the angelfish, I'm not sure, but I think angels could make the problem worse
Moved the gourami out of the 29 yesterday into a new water 10 gallon and gave him the 30 filter he is way more active and actually comes to the front of the tank the tank has the best readings i have gotten out of the three tanks i have ammonia 0 nitrites 0
Gonna get some plants and let him chill in there for a few weeks while I cycle the 29
Maybe put a cory cat in there with him got a small log that it would love