Different people have different tastes, so it's hard to know what you're looking for and would like best. IMO, KOF '02 is the best in the series hands down, for gameplay, variety, and roster (best of the '99-'01 characters + Orochi/New Face team). I'd also have to point out that if you've only played characters like Ramon and Vanessa in KOF 2000, they are TOTALLY different in '02 -- much better characters now -- play differently, some new moves, and very fun. But the backgrounds and music aren't as nice as '03, so depending on how important that is to you, it may be a factor. '01 also lacks in backgrounds and music, but is a blast to play -- very unique. And it also has a great roster, so '01 would be my second choice after '02, personally.
(To give you an idea of my taste, I'd say my least favorite would be '99, followed maybe by 2000. My favorites after '02 & '01 would be '96 and '94)
As for choosing between '03 and SVC...it's again open to taste. Obviously, you've heard by now about SVC being broken. It is. But for casual playing, I still think it's fun, and playing as the Capcom characters in SNK style is cool. If you play competetively, you'll eventually get frustrated as you begin to realize some characters have overwhelming disadvantage, in that their normal attacks can be Guard Cancel Stepped (you'll see) and punished. Personally, I'm not at a high level of play, so I'm more or less fine with it. If you just play for fun with friends, without a lot of high-end technique, that's what the game is -- fun. And as a 1-player game, I got no problems with it. Some people complain about the backgrounds (I like most of them, myself -- a unique atmosphere), and the music (I think it's fine, and a couple, like Athena's stage music, I like a lot). The dialogue between characters before and after matches, along with the endings, are excellent and enjoyable. An unrelated note: I've found I really love playing as Kasumi in this game...I like this version of her better than the KOF 2000 version.
I've played a little less KOF '03 so far, but what I played, I liked, and I do plan to get the game. Visually and music-wise, it's a step up from SVC and the last 2 KOFs. The tag system makes the game unique among the other games of the series. The game has it's brokeness, but from what I've heard, not to the level of SVC. The biggest complaint is Duolon being overpowered, but it doesn't seem to be enough to stop a lot of people from loving the game. I like the new characters in '03, like Ash and Malin...but I miss many more that aren't in the game (Vanessa, Ramon, Angel, May Lee, Shermie, etc.) I haven't played enough to comment much further than that, except that the story and endings in this game are also very good (for whatever that's worth).
Ranking the 4 games by gameplay (imo): '02>'01>'03>SVC
Ranking by looks and sound: '03>SVC (barely)>'02>'01
All of the above is just my opinion, take it for whatever you think it's worth. I like all of those games.
