I much prefer my aluminium road bike to my steel bike in just about every respect (efficiency, stability, speed, acceleration, even comfort) – they have virtually identical geometry.
That’s me, though, and everyone’s different. Preferring aluminium may make me uncool but it doesn’t make me wrong.
There’s no single “best” material. And for any given geometry the material is, to a large degree, no more than a means of achieving the tube shapes that are required in order to get the stiffness in the right place whilst balancing the undesirable factors of cost and weight. (As a large bloke, one of the issues with steel is that to get a frame with tube profiles large enough to make it stiff ‘enough’ would be both heavy *and* expensive.)
The answer to the question depends wholly on what you find are the good and bad characteristics of each of your current bikes, and what characteristics you want of your new one, plus other factors like how big you are and what you intend to use it for.