Newbie: Old Models to Avoid?

Newbie here: considering starting my plastic addiction with the Necron. This faction’s range seems to be in an interesting place where it just got a huge refresh from being the box art bad guy an edition ago, but still has a substantial amount of core models that are a decade old. That said, a lot of those models seem to be holding up well despite the age (Lychguard, immortals, vehicles). But in such an expensive hobby, I’m a little worried about buying old models just for them to be refreshed in the near future to something much better.

All that’s to say, are there any models you would generally recommend staying away from for the time being (either because they are almost certain to be updated soon, or because they aren’t generally replaceable in lists)? And, on the other hand, are there any old models that are so core that I would be holding myself back by not taking?

Thanks for the advice!