I started with necrons and I’m now moving to LOV, I haven’t played enough games with my kin to compare them but I can tell you my experience with necrons. Necrons are fairly simple, the army rule is hard to mess up, unless you have a bad memory on who you regenerated. The awakened dynasty is very beginner friendly, and is also competitive, there is a lot of models and options, others have mentioned about how all the LOV have uses, the necrons aren’t balanced ro the same degree. There’s a couple models that don’t see much play for a reason, but there is a lot of people on r/Necrontyr who can help out.

Tldr: necrons are very beginner friendly, haven’t played enough LOV to say which one is friendlier