Questions about Doran's blade,

What's the advantage? i mean whats the real advantage, i mean its is a super op wep, gets me all the life steal i require when i am laning, but you cant upgrade it to any weapons, wouldnt a long sword and refillable portion a better option? It should give you enough sustain power, and you wouldnt need to hit a minion to lifesteal (when using dorans blade).

So would that mean and are better than ? Please let me know what you prefer, and why, in the comments below. Personally i like the long sword and portion.