Unfortunately, the best way to actually build a Sith team is to follow the Rebel meta. The more Crystals you get from the Arena, the easier the overall game is. You can get more refreshes and grow far faster than trying to make your way with DS only.
Generall speaking, you want the best guild you can get for gear, but guilds are looking for well rounded rosters. And I say this as a guild leader. The first thing I look at when someone applies is their characters and gear. Without strong LS teams, you end up struggling to build up all your characters, making it less likely for guilds to want you because they're thinking about LS TB and TW. Of course, that mostly applies to peoplewho haven't already go a guild. My guess is you do.
But given enough time, that'll force you use Rebels or be pushed out of the top 100. Arenas become like a wave, with the current meta in the top and slowly expanding downward. Anyone who doesn't change ends up getting pushed further and further down. That's what happened to my Arena. There are 2 NS teams in the top 100. Everyone else is using CLS, Rey, or GK teams (with minor variations). No other teams can even break it, and it's been like that for a long time. It will happen to your Arena. Over time, more people build up Rebels and Zeta them, CLS comes back, etc. All of it is leading towards that end.
Of course, all Arenas are different. Maybe yours will be more diverse. I'm guessing that you meant you've been playing since 2016, given your G12s. You might not have that many people getting Rey this time with the difficult farming requirements. The bad news is you're probably going to get hit hard with CLS. A ton of people that missed him the first time have probably been preparing for his return. Depending on how prepared they are on Zetas and gear, my guess is you'll be seeing a bunch of CLS teams popping up soon.
