When it comes to marriage, most Muslims know that they need to look for the best in deen (religion). However, everyone's definition of religiousness is completely different.
Some require a husband/wife to read Quran daily and have part or all of it memorised. Others require that the man goes to mosque everyday and women pray tahajjud every night. Some guys even require that a Muslim woman speak/understand Arabic. Then there are people who measure deen based on the number of Islamic conferences attended, books read, or how involved one is in dawah. This is all good but what if your actions do not sink in and do not bring about a positive change?
A very long time back I spoke to a man who claimed he was Hafiz-e-Quran. I was really not expecting my husband to be one but I was definitely impressed by this fact. Initially our conversation was moderated but he later requested to speak with me privately (online). I agreed as I had a lot to ask since it was still in the early stages. Unfortunately, almost immediately, his true character was revealed. He started swearing as part of a casual conversation and this disturbed me a lot. It is one of the things that completely turns me off and I dislike keeping the company of people who swear out of the fear that I'll start it. If that was not enough, he went from suddenly proposing marriage (which caught me off guard since we hardly spoke) to wanting to "beat me" to asking me when we can meet all within 5 mins. SubhanAllah! I didn't even bother responding after that and I was completely flabbergasted. To think a Hafiz-e-Quran had such a poor character was shocking. I know this is probably a rare incident but it led me to redefine religiousness.
Any person who seems outwardly religious but their character doesn't reflect that cannot really be religious. I understand we are not perfect but there's a difference in qualities that can lead to a disastrous marriage and ones that can be worked on. Aggression and aggressive behaviour, I'm afraid, is not one that I will ever take a chance on. There's a difference between anger and aggression. Everyone gets angry and show it in different ways. Maybe they stop communicating with the person or they get into an argument but aggression is when they threaten you, get physical, include emotional taunts to break you, etc. The former can be managed provided the person is willing to change. The latter requires professional help.
Anyway, I digress. Personally for me, the most important things are a man who at least practices the basic faith - regular salah (prayer), fasting in Ramadan, avoids haram (by eating zabiha/halal foods, avoiding interest, guards himself, etc), has the intention of performing hajj (preferably with his wife :D ), gives zakat (if it is fardh on him). Anything above this is awesome. If he is actively seeking knowledge on Islam and
making an effort to become a better Muslim by keeping his actions in check then I've found my perfect match. A Muslim man or woman who is oblivious to their defects in religion isn't really going to do much to change so insight is extremely important when it comes to religion. As far as having a difficult time changing, that can be managed because everyone needs motivation from time to time.