There is one specific ability which I don't think has been discussed yet in this thread (I skimmed through most of it).
Flying: I can tell you as master of earth, this is one hurdle that is difficult to deal with. There are indeed other elements that have a hard time dealing with wings/lack of airborne creatures (entropy, life come to mind off hand), but earth has a particularly hard time with it because it is only a semi-complete element. We have no great means of addressing the problem easily. 1. Our dragons don't hit hard and are expensive. 2. In order to run a pulvy to deal with it, you are then committing to gravity quanta generation and leaving yourself more easily exposed to other battle tactics by making this commitment.
This whole concept fits in with OldTrees broad discussion of a complete element. Earth has to go to extremes to deal with this flying problem since it has no real in-element solutions. Other elements have this problem in relation to other concepts (light has no pc or cc, gravity has no creatures with a favorable quanta/attack ratio unupped), but fire is much more "complete" in this sense.
Which leads me to the next discussion: league play.
I have largely participated in league play in the past because I feel it is absolutely essential if someone really wants to take their game to the next level as far as understanding pvp. I started off last BL season in last place through the first couple of weeks and by the midway point I had worked by way up to 2nd at one point. My problem with leagues is, in an environment where the sky is the limit creativity-wise, there is a real lack of creativity promoted. If one gets too creative with their decks, they are only shooting themselves in the foot. In Beginner's League, not everyone uses grabbows or firestall, but to make a deck that doesn't at least take these two decks into account as far as counters is a big mistake. There then becomes a stigma that people using these decks are "noobs" and that they are playing unfair. On a side note: for some reason grabbows have less of this stigma than firestalls do. I ran out of motivation pretty quickly in BL to grind games in an unoriginal environment and ended up 5th. I found that events and tournaments were much more enjoyable to me because they were generally crafted in a way that promoted thinking outside of the box.
I have joined CL this season, again, mostly for the learning experience. I find CL to be more balanced in a way that there are more than two decks that dominate the meta, but I find that it is less balanced in that playing anything outside of 5 or 6 decks is again, shooting yourself in the foot. CL decks are also so quick in that I notice a lot of times the game is decided as soon as the opening hands are drawn. I am again, quickly losing the motivation to play them because I find other game modes to be more enjoyable. I have literally already played three DBH rainbow mirror matches that resulted in the winner being determined by a cointoss because of the following mechanic: Turn 1 - play QT, Turn 2 - wait for 2

quanta so you can Supernova, Turn 3 - play Supernova & Blackhole and win.
I would consider TStar to be the king of BL. He takes an aggressive approach to firestalls and grabbows in chat in that he calls out their users and makes an example of them. This seemed to have the effect that most people were scared to use at least firestalls by halfway through the season. Myself included, I made a point to focus on countering these two decks as opposed to playing them about 4 weeks into the season. My decks became categorized as the following (without getting into the specifics): Strong counters to grabbows - weak to firestalls, decent counters to both, and strong counters to firestalls - weak to grabbows/rushes.
I observed CL going through a similar transformation last season. Jen-i dealt with it by crafting his decks so that he made sure to counter both firestalls and TADAbows. xn0ize made his go-to deck (poisondial) so that he had a mathematical advantage at beating both. I've now found that the decks consist more of hard counters to each, but are highly draw dependent. CL is just a big guessing game at the moment, with the winners still tending to play "overpowered" decks that have consistent opening draws. I am still intrigued enough to play a few games here and there, but my motivation has been much less than it was at the start of BL. Tourneys/war/events are still king for me.
I would now like to take the discussion back to fire and "complete" elements themselves. It is crucial to bring other elements into a more competitive situation with these elements. Like OldTrees mentioned, this is best done by buffing general concepts within each element, without compromising the originality each style brings. Random thought: death and entropy definitely have deficiencies, but death's powerful win condition and discord for entropy make them huge competitors.
In my opinion, firebolt needs a nerf in order to scale fire back some. It has other awesome cards (immo, pheonix, rage pot, deflag), but it is firebolt's power and synergy with its weapon that make it such a huge threat. If firebolt were to receive a nerf to 2 damage per 10 quanta, I feel 7-8 other elements would not have a problem competing.
End of TL;DR text. I would really like to be able to go through some of the specific BL decks that are strong counters to the meta, but don't want to do players the disservice of releasing this information.