Suppose I have 3 unspent outputs:
tx: 3 BTC
tx: 2 BTC
tx: 1 BTC
Now I want to spend 2.5 BTC.
Which is preferred as input(s) and why?
A single:
3 BTC (Leaving my an output change of 0.5)?
Or:
1 BTC + 2BTC? (Leaving my an output change of 0.5)
I hope the question is clear.
You'll save a few bytes by spending the 3 BTC. I don't know if you would prefer that, as you may have other criteria, but that's what I would do. I'd also rather not let wallet explorers know that my 2 BTC and 1 BTC addresses are under the same wallet.