Okay, let’s get one thing straight: everyone wants an invisibility cloak. EVERYONE.
That being said, it should be obvious that I choose Hallows. Because invisibility cloak.
It’s definitely an interesting question, because both hallows and horcruxes are items involving death. What’s more, they are both items that involve defeating death.
Horcruxes involve splitting up your soul—giving up your humanity in order to evade death. Hallows involve using Death’s tools against him.
In a way, you lose your humanity either way. Horcruxes mean you have to kill other humans. The Elder Wand can fill you will an all consuming lust for power. And the Resurrection Stone can drive you insane with forgetting the line between life and death.
The Invisibility Cloak is no exception to this. You could hide from death (and everyone else) forever. But still think it would be cool to have.