The community is what you make of it and is a matter of personal preference. If you are more at home in one community and find another to be unwelcoming or "not a good fit" for you then it should not matter what other people say.
I could be an active contributing member on several SE sites. Gaming, Android or Worldbuilding are three sites that resonate well with my interests, but if I have an actual real problem then 9 times out of 10 the place that I'll find the actual answers will be in the archives of this site or with our friendly regulars in chat.
I do often get answers from sites such as Stack Overflow, but have rarely needed to ask a question there as my needs are usually simple and already asked. I lack a lot of the "deeper" knowledge to answer the more detailed questions that they get on 'Overflow, mainly because of my generalist nature. I can be classed as an intermediate/power user in several fields of computing but never a specialist.
But that's not a bad thing, I personally like to think that SU is more for the keen system generalist. We cater for pretty much anything you can do with a computer without specialising in one OS, or being a programmer, or being a systems administrator, or having your entire job focus around one specific field. If you only care about Ubuntu, then fine we have a site for that, but if you like both Ubuntu and Windows and Apple you either need us here or you have to get comfortable in two or three distinct communities.
I can bang together a spreadsheet to calculate your taxes and I'm not afraid to dabble in a bit of light Python programming to query an SQL database to make my job easier or even setting up a Raspberry Pi to cross-compile code for a microcontroller. A lot of the how to do this came from a variety of sources across disciplines and I've seen something on almost every SE site that I found interesting or useful, but the centre point for me has always ended up back here on Super User.
While we have specifically excluded several types of computing questions (such as "real" programming, tablets and phones) we are more inclusive than most sites and cater to people who like to use computers and get the most from them.
There is no site that is better for everyone, only a site that is better for you.
The people who suggest that SE has a heirarchy are the same elitists who think that Mathematics is the only "pure" field of endeavour, what they fail to understand is that in order to see the wider picture or do useful things with that knowledge then sometimes you actually need to pull up your sleeves and get your hands dirty.
From xkcd: https://xkcd.com/435