I think TOS is far superior to TNG, but it's hard to quantify. Anybody who likes TOS already knows why, and anybody who doesn't yet, well, dissecting it could ruin the experience. TOS was certainly far more revolutionary than any Star Trek after it. If you didn't live back then (I wasn't alive yet), you just can't understand how big a step forward it was from what was on TV at the time.
TNG is a bunch of technobabble and flat acting IMHO. The characters almost always act the exact same way, no matter what the situation is. There's no real interaction, no synthesis. It often feels to me like it was done by an AI rather than real people. I don't bother with the later series at all...what little I have seen has done nothing to interest me.
As for the movies, I think Star Trek 2, 3, and 4 hang comfortably with any other trilogy of movies ever made. 1, 5, Generations, and First Contact were hit-and-miss. The rest (yes, including 6) I consider quite poor and visionless. The casting of 6 was an insult.
As for what other people think of you- whether you think you're a Trekkie or a Trekker, whether you prefer Picard or Kirk, whether your friends would make fun of you or not- I personally wouldn't be concerned. People should be able to handle other people liking or disliking spaceship shows.