I've tried both. I think they have their own merits.
Don't forget, pivoting is free. Those Doom Arks have great range. The Barges are great transport killers..... but that Ark just has fantastic range in an army burdened by 24".
Personally I believe you build an army around either concept. So I think both work really well, but like Nids, Necrons have a certain list-wide synergy that have to compliment your most expensive units.
I have a good list with the Doom arks that involves a C'tan. But the list would fail with Annihilation Barges IMO.
If you really wanted to force your opponent's hand, Doom Arks are an incredible 'honey pot'. If you want to be more aggressive, and pressure your opponent, Barges are naturally better. So I guess playstyle comes into it too.
Guess I wasn't much help was I? lol
I think -nearly- everything in the dex works to some degree with the right supporting units. Don't get me wrong, we definitely have a few 'Pyrovores' in our 'dex, but not many.