For most couples, the best plan is joint tenancy. This means that you both own the whole property, which allows the survivor to take over ownership of the property if one partner dies. It makes sense if you are married or common law and would be leaving it to each other through your will, especially as, most likely, you both contributed equally to the down payment and are jointly on the mortgage.
Sometimes, it makes more sense to buy as tenants in common with specified shares. This makes sense if you are buying as business partners, or parents and children purchasing a home together. You can buy 50-50, or any other percentage share. This is helpful if you would ultimately want your share of the house to go to someone else through your estate, or you want to clearly indicate what percentage you have bought into for taxes in the future.
How you take title is an important decision. If you are unsure, you should talk to your lawyer about the pros and cons of each way so that you end up owning the house the way that is best for you.