I remember my first introduction to Smash was when I was in a computer store in Summer 2006 with my brother and they had a bunch of game trailers up on laptops and desktops. This was probably a year into me getting into Nintendo games more heavily (I mainly grew up with Playstation but I had a Game Boy and a few games). One of the trailers they had up was the E3 2006 trailer for Brawl, and I remember looking at it and being SO confused. Then the part with Snake showed up and my mind was blown (I was a MGS fan from a very young age, got to play a bit of MGS1 and got heavily into MGS2).
I then looked up the name "Super Smash Bros" and found out it was a series. I had an N64 emulator, so I downloaded the ROM for the original Smash and was hooked on it.
It was around this time that I would use pocket money to buy gaming magazines, and I would sometimes find Brawl news in these magazines. I think I found out about the Brawl Dojo through one, and since this was around the time I could use the internet from time to time in my dad's house, I started following it. A now-former friend who I met in secondary school was a Nintendo fan and we followed the updates together. I remember I would actually use my phone's 3G internet connection to get the updates daily, as my mother didn't have broadband in her house.
I remember seeing so many fake Sonic leaks that got me pumped and hopeful that he would somehow manage to get into the game (I was a Sonic fan even then). I gave up hope after a while and it became a wishful thinking kind of thing at most...then one of the magazines I bought had a picture of him fighting Link in Skyworld and I noticed that I didn't recognise this model. So I went online and found that reveal trailer and nearly had a heart attack. I seriously watched the trailer like 10 times in a row when I first found it. It was so amazing to me, like my wildest dream had come true! I also remember making a new friend around this time (who is now my very best friend), and he was saying how he liked Mario games and Sonic games and what not, and when I showed him Sonic in Brawl he was absolutely gobsmacked.
So no, Smash 4 is not the first Smash game I have been following. It is the first I have been able to communicate with others on besides one or two IRL friends, though. Even before I joined this site, I talked about it on the other forums I'm on, and with a few online friends, even before it's reveal trailer last year.
I just got into Mega Man games two years ago (mainly the X series, but I still play some of the Classics and really like them), so when I got home from doing a stressful English exam to my brother having just finished the E3 Nintendo Direct last year, and he skipped to a particular part, the Smash 4 trailer came up, and I was so happy. Then Mega Man showed up and I internally roared. It was pretty close to the excitement I felt for Sonic's Brawl reveal.
I remember on October 1st, I was discussing Smash 4 with a college friend, saying how it would be awfully disappointing if Sonic didn't return, because Mega Man is in and Mario VS Mega Man VS Sonic would be amazing, and how it makes too much sense since Mega Man and Sonic just had a crossover comic, and then when I got home and checked the daily pic, low and behold, Sonic was there, and then I found out about the Nintendo Direct, and saw the trailer, and was like "yyyyeeeeEEESSS!!!!".
Then, the day Rosalina was revealed, I was finished with my last bit of work in my last class, and logged onto the Smash 4 website because my friend was looking to see the current roster, and then I saw Rosalina & Luma there and I nearly laughed in satisfaction during class. Then I got home, saw the Direct, saw her trailer (AND that she was in Mario Kart 8), and I was so happy. That, combined with seeing her trailer for 3D World a month prior, pretty much rekindled the buried love I had for the character.
So yeah, Snake, Sonic, Mega Man, and Rosalina were the most hype reveals for me. If Layton and Reggie are confirmed, I will achieve similar hype.
And PS All-Stars was also pretty hype for me.