I like the Rat for this. I have played it against e4,d4 and the English openings. I usually have options, a chance to fight for central control, and attacking chances in the end game, whether I chose to castle to either side.
Black openings which engender consistent positions.

As it happens I have actually decided to use the Taimanov variation of the Sicilian (for the moment anyway), although the move order varies greatly I find it does generate the same positions and I'm finding a lot of the positions have the same sort of ideas as my Queen's Gambit system.
Thanks a lot for the advice.
RAC

I use "1. ... e6 against everything" as my main black opening as I found that it gives me quite consistent positions. Usually 1. d4 players will not play 2. e4 to enter the French, but 2. c4 to enter the Queen's Gambit Declined which does not give as much active play as the French, but the positions and arising problems you have to deal with are somewhat similar, like the "bad bishop" on c8 and the general pawn structure.

The semi-tarrasch Aboaisha just recommended is a garbage defense. Learn about the way computers evaluate positions before thinking you have instant equality playing that junk because your computer likes it on move 2. There is no need for 4. Nf3 or anything like that as neither retreat for the knight after 3. e4 is particularly good. Once you reach the level where your opponents know how to use the center it all but dissappears. I punched it into my database to see if I was missing something about Nf3 and sorted the games by black elo. The highest rated black player to play it was 2500 and lost to an expert.
What type of style, positions, and endgames suit you? Finding a good repertoire you like isn't too hard but we can make better recomendations if you explain more about yourself.
I guess you mean 4.e4.
This is exactly what Black is hoping for, for the reasons already explained.
4.Nf3 first does the trick, though.
Oh, and this is NOT a semi-Tarrasch (which goes 1.d4 d5 2.c4 e6 3.Nc3 Nf6 4.Nf3 c5 5.cd5 Nxd5).
You can tell how much respect I have for it that I don't even know enough theory to get the name right.
I just don't see black getting to play a quick e5 as a problem for white. After ...e5 Nf3 exd4 Nxd4 white has a center pawn, a slight development advantage, good centralization. It just looks like a good position. Granted I haven't looked that deeply so maybe I will start play Nf3 first.
It's called the Marshall Defense to the Queen's Gambit, first of all. And yes it is terrible.
4.Nf3 is better than an immediate 4.e4 because it prevents black from the counter-punch e5. To illustrate it with ridiculously hyperbolic metaphors, by playing the Marshall Defense Black kicked himself in the shin and is currently writhing in pain on the ground struggling to get up. With 4.e4 you reach out your hand for him to pull himself to his feet; he's still visibly in pain, but he sees some light on the horizon promising relief. With 4.Nf3 you start laughing at him and kick him some more instead.

The Slav Proper (not Semi-Slav) and Caro-Kann
1.d4 d5 2.c4 c6 3.Nf3 Nf6 4.Nc3 dxc4 5.a4 Bf5
White can try the gambits 5.e3 or 5.e4 too btw and you will see this kinda often.

As black I really think you have to improvise more based on the circumstances of the particular game and your opponent. For instance, certain lines are great for equalising and drawish positions, whilst certain lines give more chance of a win but are more dangerous. Up to a certain level of opponent d5 will more often than not give you an equal fighting chance against d4 and in quite steady positions. But with high rated players an indian defense may be more appropriate.
Against e4, I don't think I could recommend a steady way of playing, as all the best ways to respond are more dynamic and dangerous, in my opinion, these being e5, the sicilian and the french.
The Scheveningen Sicilian structure is a good one for getting your pieces into position, and there is really not much white can do thats any good to stop you in the first 10 moves or so.

- B10: Caro-Kann Defense - http://goo.gl/okwwX
- C00: French Defense - http://goo.gl/t2Uhm
- E90: King's Indian Defense - http://goo.gl/Lur6w
Good luck.
What opening for black leads to consistent (and good) positions? That's a good question. Maybe the French defense vs 1e4 and the Nimzo Indian paired with the Ragozin against 1d4. Here is a run down on my experiences in the openings.
Like many people, I first learned and played double king pawn openings. Then I followed fashion of the time and played the Sicilian for many years. I've also played the French.
Now I have returned to the double-king pawn openings. They seem to be the most fun and give the earliest wins against weaker or less prepared players. A challenge here is to find an answer you like to the Ruy Lopez. I've never played the Marshall counter gambit, but it really is good. The Open Ruy is fun, but requires study and experience. You must have an answer to the King's gambit that suites you. 2...Bc5 deserves to be considered. There are many tricky lines in the DKP openings. It takes a lot of work but I find it rewarding.
The French defense leads to interesting maneuvering games, and to pretty consistent play. This might be a good match if you play the Queen's Gambit Declined. The downside of the French, in my opinion, is that you often have less space. I sometimes felt that I needed two victories to win. The first to get equality, the second to actually win the game. Maybe it is that way in other openings too. You will need specific answers to 3Nc3, 3Nd2 and even 3e5. Maybe 3Nc3 Nf6 and 3Nd2 Nf6. 3Nc3 Bb4 is interesting, but the poisoned pawn variation is critical.
The Sicilian depends a lot on the variation chosen. I play the Classical. Black's biggest problem here is the Richter-Rauzer. Black should probably play something else. The Najdorf, Taimanov/Kan, Sveshnikov, Dragon are all respectable. But you must also face "sidelines" such as the Alapin, Closed, Grand Prix and Smith-Morra gambit. You will never find peace in the Sicilian counter attack (better known as the Sicilian Defense).
Vs. 1d4, I first played the King's Indian defense, then the Nimzo-Indian, now the Queen's Gambit Declined. Some players get consistent play by answering all moves with 1...g6, or 1...e6.
The Nimzo paired with the Ragozin (Vienna) gives pretty consistent play. If you like certain lines of the Nimzo, then the Ragozin and Vienna just feel like another Nimzo line. The Nimzo is, arguably, the gold standard response to 1d4. It's hallmark is flexibility more so than consistency, as play can resemble the Benoni, Dutch, Queen's gambit or Old Indian. I usually choose a queen's gambit declined structure. But against the Leningrad (1d4 Nf6 2c4 e6 3Nc3 Bb4 4Bg5) I play 4...c5 for a Benoni-ish game.
I rather like the Queen's Gambit Declined, but the exchange variation is strong enough to give one pause. In my practice the exchange variation has led to cut and thrust play. But white has more than one line that score well in professional play. If white does not exchange, I suggest the Tartakover variation. It is positionally sound but requires implementing tactics. I think it best to resist the temptation of playing the Cambridge Springs defense. It is tactically motivated and can lead to quick wins. But it is positionally suspect and black struggles in the main lines. If you like the QGD, then you are pretty well set vs. 1Nf3 or 1c4.
Whether you play the QGD or the Nimzo/Ragozin, you may face the Catalan. I've looked at many interesting side-lines, but maybe the main line is best. For one thing, you are less likely to be "move ordered" after 1Nf3.
One GM recommended symmetrical play on move 1: 1d4 d5, 1e4 e5, 1c4 c5. The recommendation is consistent, but each leads to a very different game!
My games all look pretty much the same in the middle game. Playing against a bunch of different Pirc players is much different than playing it yourself every game.