Sif, Jane, and Enchantress have been his three main love interests. Hela and Valkyrie to a lesser extent. To be Thor's wife means to be both the head of household, someone who can hold their own in battle, and possible be a commanding queen as well.
Sif-Sif is in many ways perfect. Thor can love, trust and respect her. She is a warrior to fight beside. I can even see her becoming a mother eventually. I just can't really see her as a queen. To me, she has never had the same commanding presence required of a ruler nor a willingness to use power.
Jane-I could see there being love, trust, and respect in this relationship. Jane is already a mother. Being a warrior is not an absolute and she could be taught enough about fighting to survive or maybe even some magic. However, I can't see her being queen. I think the whole god thing would get to her. She is from too different a culture. It would take her years if not centuries to adapt. Of course, if it is one thing Thor has it is time. I still think Sif is better due to not having a cultural barrier to cross and the warriors aspect.
Enchantress-In many ways she is the best choice. She served as queen during the Regining. I think their could be love and even to a degree trust and respect there if she ever mended some of her ways. She is certainly capable of taking care of herself and holding her own in a fight. She has no qualms about using power. The problem is her morality does not match up with Thor's own. He would have to keep an eye on her to keep her from going too far.
Hela-She shares many of the same strength and weaknesses as Hela. The main problem is she has shown attraction to Thor, but not vice versa.
Valkyrie-I think she would in a way be the best. She is in many ways like Sif, but to me has always had a bit more of a commanding presence and comes off to me as more willing to give orders than Sif. I could see her doing a good job at it. I could even see her being a firm caregiver if required.
My first thought was...Sif. Pretty much the front runner anyway.
And then I thought...
But what if Thor was forced by circumstance into a marriage of convenience? A war between, say, Asgard and Olympys, which ended in an uneasy truce, but needed a marriage between Thor and, for example, Venus to ensure the peace lasted?
That could result in some nice storylines.
Might even give the main book a much neede kick up the a**