There are advantages and disadvantages to both a joint tenancy and a tenancy in common. Which one is best for you will depend on your individual needs and circumstances.
Many married couples opt for joint tenancies because they don't perceive any advantage in defining separate shares - particularly if they want the property to pass automatically to the surviving spouse if one of them dies.
Tenancy in common may be more suitable for couples where one spouse has children from a prior relationship, unmarried couples, brothers and sisters, parents and children, or business partners - since in these cases one of the title-holders may not want the other owner(s) to inherit their share, at least not the entirety of it.
If, for this decision, you plump for a tenancy in common, you must remember to write a will, since if you fail to do so the laws of intestacy will determine who gets what - which may defeat your objective of rejecting a joint tenancy,
For example, under the intestacy rules, your spouse would receive all of your personal chattels (e.g., clothes, jewelry, etc), a statutory legacy of £250,000, plus a life interest in half of anything that remains - this could swallow up virtually all of your interest in the property.
Meanwhile, your children (or their offspring) would receive the other half of anything that remains of your estate and the capital that is left after your spouse's life interest ends. Thus, they could end up with nothing or may have to wait a very long time to receive anything from your estate.
** Additional Information & Advice **
Depending on your circumstances, however, you may want to speak with a solicitor who specialises in conveyancing and/or will preparation. You can find a solicitor in your area for free via solicitor matching services, which can also help you to understand the best course of action and whether you are ready to hire a solicitor.