1...e5 or 1...c5 against 1.e4?

The eternal question of what to play against 1. e4. For myself the Caro-Kann is the fall back as I have general issues with both 1.. e5 and 1..c5.

1.. e5 I almost never play. It is incredibly booked up at all levels and there are simply too many variations. Suppose we always go down the main line, Ruy Lopez Breyer variation, that I am happy with. However just some slight deviation may take me out of book. And if it is not a Ruy Lopez at all such as 1. e4 e5 2. Nf3 Nc6 3. d4, the Scotch game is completely different and usually enough to take me out of my comfort zone, as I really don't have a good line against that.

1.. c5 the problem is that it is a very aggressive, no margin for error type of opening. If black plays it correctly black will end up equal or better, but if something goes slightly wrong the position collapses and it is suddenly GG. There are a lot of lines and variations to look at. If I play 1.. c5 I usually play the hyper-accelerated dragon (I read a book on this opening), which has relatively fewer variations and the worse black can face is probably the Maroczy bind, which I don't think is that terrible.

But if I may offer from my experience with 1...c5, I won't say I have never lost a game. Nor will I say I have lost less, than I did playing 1....c6.

But I will say I have always gotten at least some counterplay, for my troubles, playing the Sicilian.

I have always had a fightng chance.

Then I compare that to my playing the Caro-Kann. When things went bad in that opening, all I could do is cower in the corner, watching as my opponent amassed his final assault.

Going down fighting is better.

All established openings are good and it depends on what fits your style of play, so you can't simply ask others for their opinion on what's best: it's like asking what's the best shoe size.

I suggest looking at a book that surveys the openings in terms of the ideas behind them - even the old Reuben Fine book, Ideas Behind the Openings is still good.

You say, for example you've played 1...c6.  Do you understand that the point is to get the QB outside your P-chain before ...e6 makes it a "Bad Bishop," that if White plays the Advance you can undermine his P-chain with ...c5 or ...b6 or ...f6 and that playing ...Nbd7 not only supports those moves but prevents White from setting up a N-Outpost at c5 or e5?

You should understand those principles about all the variations you're considering in terms of Najdorf (...a6 prevents Bb5+ -why is that good? It also helps prepare for a Black Q-side expansion), Dragon (what can the fiancettoed B do for you?), etc. Sicilians - know WHY the opening is the way it is and if it fits your style.

I used to be an e4 player when I was younger, but about 6-7 years ago (I was a 1300 in 7th grade) I got enough money to buy my first chess book, Play the Sicilian Dragon by Edward Dearing.

I read it completely during the summer and the beggining of my 8th grade year but the main problem for me was that I knew all the lines, but most lines involve the Rook sac on c3 and outplaying your in the endgame with a Knight and perfect pawn structure vs rook and bad pawn structure. (assuming the game isn't over by move 19 because of a small inaccuracy by either player) and I didn't know much about endgames so I would lose many games. 

It wasn't until I put emphasis on my endgames (specially the endgames that arise from my openings that my rating skyrocketed 600 points in about 15 tournaments. 

My point is that my opening knowledge was basically useless until I knew how to finish games. My two cents would be to look at the endings that usually arise from the opening you want to play, study it, and then study the opening. 

Ohh, and although the Najdorf is highly theoretical, so is the Spanish, Italian, and even the Scotch, so don't worry about people thinking you're too low rated to play an opening, that's bs, if you feel comfortable play it. 

I've played the Najdorf as well, and I like it, but one thing you must know is that sometimes your king will be safer in the center, so you're gonna have get comfortable with those positions.

... I have Fine's book, I just have the impression that so much stuff went on in the openings since this book was published that I am not sure if reading it will be a big help. In the Caro-Kann, for example, there are some hair-raising sacrifices that were absolutely unknown in this time. ...