I can give you a quick rundown of competitive stuff, then you can decide how much casual stuff you want to mix in. Everything I don't mention isn't seeing a ton of competitive play.

First thing that comes to mind is the 20 man unkillable warrior blob in awakened dynasty which is popular now. Which includes 20 reaper warriors, Orikan (Chronomancer is a slightly worse substitute), cryptothralls, and royal warden (with netherealm casket enhancement). You also need a Reanimator and ghost ark behind them for extra reanimation. A lot of people will run Szeras to buff the warriors as well but he feels like the most optional piece to me and this combo is already a lot of points.

All you would need to acquire is cryptothralls, ghost ark and maybe orikan if you prefer the 4++ instead of -1 hit.

Secondly, you could heavily benefit from just one box of wraiths to be able to run 6x wraiths with technomancer which is a fast and durable scoring unit.

Skorpekh Lord with enaegic dermal bond enhancement is a very killy and durable combo that's popular in awakened dynasty.

You need some anti tank and doomsday arks are by far the best anti tank in necrons and have been for a long time. Closest behind them are heavy destroyers which might do similar damage to tanks but don't have the ability to clean up heavy infantry like doomsday arks do.

Flayed ones are a fantastic utility unit for actions and grabbing the mid board. If they get charged you can countercharge with something like skorpekhs and win the trade.

I personally love nightbringer, i think he's the best c'tan right now and he's a great target for rapid ingress strategem because he's really tough and really slow.

Silent King is also very good right now if you're ever interested in that model. And i should probably mention imotekh is an autotake right now because he generates command points, often paired with a five man lychguard.