Thank you all for the answers people. Sorry for being late, I spent some time playing and comparing both the servers. I guess I should have done that at the beginning. Opening this thread here instead of seeing both the servers myself seems like an impatient action. First off when I opened the thread I had been playing for around two weeks, it was not based on a one or two days experience so the time and day of the specific post is irrelevant. Also I was mainly judging by the faction fleet, not planets.
And here are my resuls; Numbers are around the same on fleet, sometimes one has more, sometimes the other. But the difference is never significant. On Malgus, planets are considerably more crowded than Star Forge. Considerably, but not drastically. EU community is far better than my prejudice, but still there are downers. Did not come across any annoyance or immaturity in US. The planets I am talking about are the early ones, I had second story companion when I opened the thread and now I have third. So I do not know about endgame-expansion/dlc planets. And given how inconvenient my play time (evening to night after work) is in the US due to the timezones, Star Forge having same or close (sometimes even more) numbers than Malgus is VERY impressive. Interestingly, regardless of numbers, I visually observe more characters moving around-doing quests in Malgus (which I like), and usually more chat activity though not always pleasant with pointless bickerings. Also I only have experience with Republic so far, do not know about the Empire side of things. My idea is to play every storyline before i decide my main, but I doubt I will do the same comparison by the time I create my first Empire character. I am sticking with Star Forge thanks again everyone.