As stated above its based on individual preference and taste. However...there are certain themes such as the optimism, intellectualism, and hopefulness I do believe are the foundations on which the franchise rests. And all Trek's showcase these foundations in different ways.
If I like it - it's real Star Trek. If I don't like it - it ruined my hopes, dreams, and childhood memories.
I don't think Discovery depicts the same world as The Original Series, but I still like it and consider it "real" Star Trek.
To be serious for a moment, having had family members who were actually sexually abused and assaulted as children it infuriates me when someone casually claims that a slight change to something they love is "raping their childhood." It's a ridiculous and insulting comment, and I wish people would stop saying it...
Oh I completely concur, Disco is brilliant and these 14, soon to be 15 episodes of its first season are the very best opening season of any Trek series. Fact. Having said that, given that Beyond allegedly under performed and a Nu-Trek IV (with or without Tarantino in charge) is seemingly not occurring any time soon, Trek is far from being the dead parrot it was in the mid-noughties, it's not in the rudest of health really.
This is the point people are often missing, it's an opening season. Apart from TOS (obviously) no other trek show has had a first season which could hold a candle to this.
User expectations are often rather disconnected from what someone thinks is true and what is in fact true. Same here.
Anything produced by Desilu, Filmation, Paramount, Bad Robot or CBS is real Star Trek. Anything in my head canon is real Star Trek to me.
Which is of course every bit as valid as my own subjective take, but can you really watch TNG's first season next to this and claim it's better? Really?
I don't like much about the first season of TNG, it seems to fair worse each time I see it, yet it engendered a hopeful spirit. I still enjoy TOS because I think the corniness suits the era (TV era that is). Voyager's first season (for me) is great. Discovery is a mess it lurches from one cliff hanger and shock and awe scene to the next, leaving plot holes and unresolved nonsense in its wake. The acting is good but the story is dreadful.
On TNG we agree, season one was truly awful, as for VOY I must confess I barely remember much of it's opening season beyond "Caretaker" and the re being lots of Kazon, that forgetting itself seems to suggest I didn't think much of it at the time, but then I'm not a huge VOY fan anyway. DS9 season one was ok, but it didn't (for me) hit it's stride until the Dominion showed up. The only trek which bucks the trend for me is TOS whose first season arguably remains amongst the best the franchise has to offer, alongside the middle seasons of TNG and latter day DS9.
I can say this for Discovery, it has given me a deeper appreciation for some Trek I had dismissed in the past.
I'd watch TNG's first season over Disco any day. At least we didn't need subtitles to understand what Worf was saying.