Against, e4, pick one or two defences, just for the sake of versatility, also I thought I had to spend a lot of time trying to figure out how to counter varius d4 lines, then I switched to the dutch, Charms, against e4 try e5 c5 Nf6 and e6 pick the one you do best with
Beginner: Choosing opening line to learn against 1. d4

Try the Queen's Gambit Accepted. It is easy to learn and filled with simple plans. Plus, a lot of white players will play dubious lines. Here is one of my favourites:

too many pawn moves, the Dutch is easy to learn, play and best of all flexable enough to handle almost any black plan

I DAFS and found a video on Isolated Queen Pawn for anyone interested in this thread.
http://www.chess.com/article/view/video-series-on-isolated-queen-pawns

Try the Queen's Gambit Accepted. It is easy to learn and filled with simple plans. Plus, a lot of white players will play dubious lines. Here is one of my favourites:
3.e4 does not deserve a ?!, it's a perfectly ok (and very aggressive/ambitious) move routinely played even among strong GMs. 3...e5 is one of the possible answers, logical and perfectly ok but not necessarily the best. The fight gets complex and unbalanced if white doesn't play the horrendous 4.d5?.

Hmmm...not really i think. It requires a certain skill to decide when you should set up a stonewall and when something else (it's not effective against every setup white can adopt). Moreover against the 1...f5 move order white has tons of dangerous attacking sidelines that might not worry most experts but are genuinely scary for the average club player; as a beginner i wouldn't want to be on the black side of these lines. The 1...e6 move order avoids this but you have to be happy with a french after 2.e4. But the really important issue is that the stonewall doesn't lead to the sort of open fight that should be the major battleground of an improving player. It might be a good defense for an advanced player, but i suspect that employing it too early might harm the chess development of a beginner.

Hmmm...not really i think. It requires a certain skill to decide when you should set up a stonewall and when something else (it's not effective against every setup white can adopt). Moreover against the 1...f5 move order white has tons of dangerous attacking sidelines that might not worry most experts but are genuinely scary for the average club player; as a beginner i wouldn't want to be on the black side of these lines. The 1...e6 move order avoids this but you have to be happy with a french after 2.e4. But the really important issue is that the stonewall doesn't lead to the sort of open fight that should be the major battleground of an improving player. It might be a good defense for an advanced player, but i suspect that employing it too early might harm the chess development of a beginner.
Well often black will pawnstorm or "piecestorm" the kingside and things can turn nasty so it's not necessarely a static/boring opening

Nowhere in my post you can find a reference to the supposed boringness/staticness of the stonewall. As you rightly say the stonewall played the classical way is anything but static, it might in fact be bloodthirsy opening choice. This doesn't change the fact that it leads to closed positions in the centre, which is not what a beginned should play.
I am surprised looking at number of posts on chess theory even by casual players. I don't know anything except the rules, infact i came to know about the enpassant rule only after joining this site. For example i feel one can reach a live standard rating of 1450 or even 1500 on this site by knowing only the rules and not knowing anything else, not even hearing about the name of any opening. Do you people agree?
Totally offbeat but scores very well in my mega-database:
Mexican Defence
Advantages of this system:
(1) Most top engines think Black equalizes easily
(2) In my Mega-Database (~5.5 mio master & semi-master games) it happened 1542 times, and White could only score 50.4%.
As a comparison: After 1.d4 Nf6 2.c4 g6 White scored 55.2%. So this is one more indication that this 'Mexican' System is stronger than it seems to be.
(3) This system is widely unexplored, not much theory is known about it. So the risk that a White player may have learned the book moves till move 25 (that'S what they could've done in some King's Indian or Queen's Gambit Variation) is very low, and so most likely both - you and your opponent - will quickly get to positions where you can actually play chess, and not so much a game of 'Who has learned more variations?'
(4) It looks cool and what is best about it: It's 100% sound, you don't gambit a pawn for some dubious compensation, and certainly if you play reasonably good moves (at least tactically) nothing can go wrong (just trust the 3000+ chess engines, they think 2...Nc6 is a really strong move).
(5) It's also a good psychological surprise weapon, because most White players may never have seen this system, they will automatically think that 2...Nc6 is a bad move and then they'll somehow want to refute it (although there actually is no refutation). That's when they often get the temptation of sacrificing material (unjustified), or may try risky moves with a higher likelihood (because 2...Nc6 looks like playing anything with White should be sufficient to get an advantage). In any case an opponent who plays more carelessly is also more likely to blunder, so good news for Black.
Well, that's a suggestion if you don't want to learn hundreds of variations until move #25 (like you're supposed to do with KID or Queen's Gambit), because the amount of known theory for the Mexican Defence can be learned more quickly, and there's hardly any theory available for it anyways.
lg

The downside is White will have a large pawn center, chasing Black's Knights around,creating a strong attack. He also hems his c and f pawns, which are used to counter attack white's pawn center.The upside is White is probably not prepared for this move, which makes it quite attractive.It is especially attractive when you memorized the theory down 10 moves.( You half to memorize much more when you play a main line opening)
Good luck
CHCL

Dutch may not be popular but that doesn't make it unplayable even in high level.
But for a beginner , Tarrasch is a more than excellent choice.Stay with the Othodox defense of Queen's Gambit ,there are alot to be learned there and many do the great mistake to bypass it and "jump" to defenses like King's Indian leaving huge gaps on their middle-game knowledge.
Excellent choices are also Lasker's and Tartakower's defense(maybe for later).Both are based on understanding and not on memorising lines.

Why is the Dutch so popular? I mean people comment how great this move is,( which I am not saying it isn't) but I never see anyone use it.

Openings is a matter of fashion , and even grandmasters don't know why some lines or openings , although not bad ,are completely forgotten at times.

"The most important novelties are hidden in the games of the old masters." Savielly Tartakower.
Old openings have the advantage of being well tested and ill remembered.A.S.
That is good advise to remember.

Why is the Dutch so popular? I mean people comment how great this move is,( which I am not saying it isn't) but I never see anyone use it.
I think the dutch is popular because typical queen pawn openings are traditionally positional as opposed to the tactical nature. Most king pawn players are lovers of the tactics, so playing the dutch vs 1. d4 creates an immediate imbalance where tactics can be a larger part of the defense. the only real downside to it is the queen bishop tends to lag behind in finding an active role. As for the reason it's seldom seen is king pawn players tend to outnumber queen pawn players by a large degree, and there are also a number of other defenses employed against it as well, such as the tarrash, pirc, etc.,
For anyone who is intersted I am going to setup some unrated online games where I play the Tarrasch opening as black. Send me a PM or friend me with a note and I will set up the games.