I don't think so, I don't really like Fire with Garbodor being a thing. The other decks are cool, but I don't have the money to drop on 3-4 Shaymins so I can effectively use Ninja Boy.
Tbh, I don't think any deck is standing out to be the best. Every deck has massive flaws, so your goal is just to mitigate the flaws. I will mainly focus on the flaws for the sake of time, but all of these decks have positives, for example, Mega Sceptile is one of the hardest decks to take prizes from and even when you do it recovers quickly.
Mega Sceptile- Low damage, Cloggy hands, and having a decent non-EX attacker.
Mega Ray- The deck that everyone is trying to counter so you are going to have to constantly deal with Parallel City and Zoroark, which you can play through, but I don't want to play the deck that everyone has a target on.
Primal Groudon- So easy just to out play this deck, the energy investment is way too high which leads to over investment onto one Primal Groudon.
Mega Steelix- Honestly, this deck seemed really bad, like pure awful but, I have noticed how effective just soaking up damage with Shield Energy, and hitting hard with Strong Energy is. Still, prone to bricking hard, and you can't wall behind Carbink because of Garbodor.
Volcanion- So many rough starts with this deck, very prone to just "Failure to Launch," type of losses. With Garbodor this deck just loses against anything that isn't Sceptile.
Mega Mewtwo- One of the more simple decks to play, and super easy to counter play against. Decks that have low energy attacks (Mega Sceptile), can just make the Mega Mewtwo player over extend and then get punished. This deck is definitely one that stifles creativity due to it punishment of using Abilities and high Energy attacks.
Darkrai Giratina- Arguably one of the strongest T1/T2 decks with the ability to easily deal 100+ damage. However, with Garbodor you can't wall behind Giratina for long, and Mega Mewtwo can just punish your Giratina. Also, the deck has a lot of variation in how good it can open so you can't get consistent results.
Zygarde- One of my more liked decks, I think it has a lot of potential but again, cards like Garbodor can just ruin your day. The deck also loses some cool stuff from rotation like AZ which isn't too big, but still an issue.
Yveltal Garbodor- Mega Mewtwo will ruin this deck, so I would say no.
As you can see, all decks that have a possibility of being good are flawed. Pick which one you don't mind the flaw in, or you think you can mitigate, and play it. I personally think Mega Sceptile is really good, you can play under Garbodor, take hits from Rayquaza, and out grind any other deck. For me, I can make a more consistent version of Mega Sceptile, add Giovanni's Scheme to get more damage, and add Lugia from Fates Collide, this doesn't fix the flaws, but it does aid them. The biggest thing is just test, test, and test, find the flaws in the deck, look at the card pool to see what you can do about it, and do something about it.
Edit: If you have an issue of what to invest in, just invest in something flexible. For example, if you buy Darkrai Giratina for lets say $230 and you play the deck and you want to change into a Yveltal deck, then you already have a lot of the basic components, you just have to spend maybe an extra $50 to build the Yveltal variant you want to play. The big cost cards are going to be staples like Max Elixir, Fighting Fury Belt, VS Seeker, Shaymin-EX, and Trainers' Mail, after that you probably won't spend more than $60 to complete a deck.