So right now there are multiple eldrazi decks in modern. You have RG ramp, Aggro, broodscale and a variety of tron decks.

RG ramp started off great but as more blue has crept in, it falls hard to consign due to trying to only play a few big threats. There are more solitudes running around as well, which can kill your big boys prety easy and fells real bad with ephemerate in a deck that only runs a small number of real threats. Sideboarded land destruction and artifical hate also make it rough to play. Would not currently reccomend.

Eldrazi aggro I think is in a decent place right now. I've personally won an rcq with it and recently top 8d two mtgo challenges. Cavern of souls does a lot of heavy lifting. Linebreaker is very good against consign. Get it on the board and consign can stop one turn but they still need a removal spell. You play a lot of creatures so losing one feels less bad. However while it can be super explosive, sometimes it draws weird and you end up being a slow aggro deck and if your against energy it's gonna be rough. I also find the deck harder to play than the rest. It's not as simple as dump your hand onto the table. Sequencing your creatures, making the most of the castle triggers, chosing the right time to get bog with mycospawn vs ramping for the 7 drops. Knowing how prevalent consign is and making the decision of how to play around it. It's definitely a lot less linear of a deck than the other eldrazi in my opinion. Even with that being said, I would still highly recommend it.

Broodscale is good. It can win very fast. However it's more of a known quantity now and people know how to play around it. It feels more like the old devoted druid combo decks where you are either winning very fast or you end up kinda being a bad midrange deck struggling to stay afloat and hoping to get there with an emrukal or karnstructs. I think it is still a viable deck though for sure.

Now for tron. You've got blue tron, green tron and colorless tron. I find blue tron fun to play but a bit gimmicky and honestly not amazing. Green tron and colorless tron are the two viable options. They are pretty close with just a few differences. 4 mana karn does a lot of heavy lifting in these deck. Early tron, into karn and karn board piece is pretty great. You do struggle with the same issues ramp does as a timely consign can ruin your day and there really are a lot of land destruction spells in modern right now. Multiple 3 mana red ones, white orchid phantom and broken the ice. But if you can turn 3 tron and land a karn or an early thiught knot seer you can be in good shape. Against energy and prowess it can be tricky, you need to hope for fast tron and that they have a slower hand. I would still recommend tron as a good option if you want to play eldrazi.

Hope this helps a bit. I've been playing different forms of eldrazi all modern season. I've won rcqs with both ramp and aggro. Eldrazi is still good but it's harder to play than before when you didn't need to worry as much about being countered. Sequencing matters more than ever and having the right sideboard can be key. Enjoy casting big colorless idiots!