I support and respect canon. Canon tells me that Dean has never shown non-platonic interest in any male-shaped or male-identifying entity until he met Cas. There are homoerotic overtones in Dean and Sam’s relationship, but Dean is in love with Cas. Dean is primarily romantically/sexually attracted to women/female-shaped entities. Cas is not the sole exception, but he was the FIRST EVER male Dean took a non-platonic interest in, and their relationship has grown from strength to strength.
Canon tells me Sam is Dean’s soulmate - but canon also tells me Cas is Dean’s one True Love. What’s the difference between a soulmate and a True Love, you ask? A soulmate you can’t choose- a True Love, you can. And I think we all know which Dean prefers, out of Destiny vs Free Will, don’t we?
I understand Wincest, but Destiel will always, ALWAYS be my OTP.