If you favor the Warrior horde,36-38 is about the right size for any reasonable game. A single 20 man unit supported by two, maybe three, arks, two of which have 8 or 9 warriors and 1-2 destructeks inside (Depending on how many Overlords you brought to the table). The 20 man has an orb in it and maybe another RC member if you have 2 OLs. Stormtek with LF is advised in this case. Wyches and other assaulty things die horribly to the LF and it gives your Warriors a fighting chance to get out of combat so they can shoot as soon as possible. That gives you two units to score late game as you can take your Arks and drop their contents onto an objective.
If you want to do that you need one of two things, and that is long range firepower, something Necrons do not get in quantity or for cheap, or something that can fight in CC, something that Necrons once again do not get in quantity or for cheap. Necron strength lies in close range firepower; Everything else is a specialist role. Our only gun that shoots over 36" is the Doomsday Cannon which costs 275 points. Our best melee fighters are around 45 points each plus whatever HQ you put with them to buff them or keep them alive. This includes Wraiths, Praetorians, and Lychguard, the first two likely having a Destroyer Lord with them and the last having an Overlord and likely a Veiltek.
Introducing melee units forces you to shape that HQ to the melee unit as it basically has to go with them to cover their weaknesses or give them the buffs that really make them worth it (Preferred Enemy on wraiths with anti-armor punching power, mobility and a 2+ save to tank the AP3 shots in Lychguard, etc).
The third and most reliable option is to have mobile fire platforms that can chase down kiters and kite assaulters. This is why barges are so good for their points, they fill a critical role in the army that nothing else can quite do. Being skimmers makes them able to force the enemy to deal with terrain that they are able to ignore, and also be unimpeded by terrain when giving chase. Being AV13 F/S helps too.
A pure warrior blob is, surprisingly, terminally overspecialized. Melee armies will eventually make it to CC where it will either be a stalemate or a tragic loss, and longer range firepower will just kite you to death. Mind you, theres only so much board for them to kite on, so after a couple turns, you'll have backed the into a board edge, but thats still a couple turns of shooting they get on you. Thats why you need the Ark support for any warrior blob army- You can make it work, as long as you do it right, but it will not be as effective as a truly synergistic force.