I've played all of these decks so I'll explain why you should get either Synchron or T.G.s and I'll see if I could have a freind of mine explain resonator since he can do it more justice than me.

Synchrons have a pretty linier game plan which is just normal summon Junk Synchron and Synchro climb into Either Shooting Star Dragon or Stardust Warrior off that single normal summon. It's pretty fun the first time you do it since you get to watch 3 summoning cutscenes of Junk Warrior, Stardust Dragon and Shooting Star Dragon. Though personally after playing the deck for awhile it can get a little boring with the 1 linear combo. Another combo they have currently is to summon Quick Draw Synchron by discarding Mecha Phantom Beast o lion, when sent to the GY O lion will summon a level 3 token. You then use both of these to Synchro Summon Junk destroyer. I've also seen some other Synchron use other tech cards like a super Quant level 5 that's special summons itself and Link Destoryer which is another level 5 that can special summon itself but can destroy spells and traps. The deck itself can be petty expensive since you'll need to buy 3 structure decks of Stardust nexus and go into a few boxes to get some cards like tuning and Junk Destoryer. We might get some new Synchron support in the next box which might change the way synchrons are played. Though it's an assumption based on another assumption so it's not guaranteed. We'll just have to wait and see. 

       In Summary: Fun anime deck that used 1 combo most of the time. It can be pretty pricy since you'll need to go through some boxes to grab certain cards. As well as buying 3 Structure decks of Stardust nexus.

T.G.s are a personal favorite deck of mine if you couldn't tell. The thing that sets them apart from other Synchro decks is that Synchro Summons on the opponent's turn. Their main combo enabler is the Level 5 Synchro Tuner T.G. Star Guardian, which lets the deck recycle T.G.s from the GY and special summons them from the hand. As well as having the effect to Synchro Summon on a quick effect. So you can Synchro Summon monsters like Ruddy or Black Rose Dragon to Nuke the whole feild or Crystron Quangrandrax which can banish up to three monsters in feild or GY If it's Synchro Summoned. The deck is also able to access a variety of tool box Synchro Monsters to help with many situations such as Metorburst to deal with battle hand traps, Samurai Destoryer to deal with battle effects, Battle Wasp to go for OTKs, and Shiriuai Squiresaga for non targeting Destruction. These are just popular examples but you can fit most generic synchros into the deck and be able to use them. The deck has a variety of combo lines which keeps the deck fresh and fun for me personally.

The deck can get a little pricey to play at full power since you would need to open the T.G. main box Atomic Theory a few times and then dig for the other generic Synchros the deck likes the run like Battle Wasp and Shiruai. But I've made a f2p decklist that needs only cards from 1 full box opening of Atomic Theory, 1 ruddy Rose Structure deck and the Trishula Bundle. It's pretty decent and can get to Legend, I haven't tested if it could get King of Games, but full power T.G.s can definitely Kog no problem.

         In Summary: Pretty unique combo deck that can access a variety of generic synchros and can Synchro Summon on your opponent's turn on a quick effect. A decent f2p deck can be built but if your willing to invest into the deck more then you'll have a strong deck that can Kog no problems.