It may not be what you initially think. A terrible scenario is to fight for an outcome and win, only later to discover that it really doesn't suit you, and your new lifestyle. Clarifying your needs starts with understanding the different types of custody. There are three main custody arrangements: sole, joint and split.
In sole custody, children live with one parent. That parent makes all major and day-to-day decisions for them. Major decisions are those involving educational, medical, religious and extracurricular activity choices. The non-custodial parent usually has the children on alternating weekends, with perhaps one or more overnight visits on the intervening weekdays. Holidays alternate between parents.
With joint custody, there are two aspects. Joint physical custody means children live in two residences. Typically, they will spend at least one third of the time living with one parent, and the remainder with the other. There is a variety of formulas commonly used to divide the time. Joint legal custody means that parents share responsibility and decision-making authority for the kids equally.
Split custody is less common. It's an arrangement in which children spend extended periods of time with one parent, and then the other. If there's history of significant conflict between a child and one parent or between siblings, or an older child wants to live with a particular parent, split custody may be a possibility. However, the Courts tend to frown on it, and view it as being disruptive to the children.
To decide among these alternatives, you'll especially need to consider your respective work and travel schedules, and your children's school-related and other activities. A successful arrangement has flexibility, and can accommodate future changes.
Think carefully about what you want. As a single person, you may now need more time and space for yourself. The reality is that at some point you might want to start dating. Consequently, an arrangement that permits you sufficient time to pursue a new relationship is to your benefit. It's healthier for you. The positive outlook you gain from feeling there's opportunity for a better life will have a correspondingly beneficial effect on your children.
Additionally, if you meet another potential partner, that person may have a different feeling about children from yours, either generally or about your kids in particular. It may require a custody arrangement that gives you more freedom to make a new relationship work.
Consider a custody plan that gives you enough latitude for growth, and then explore ways to negotiate that outcome successfully with the help of your attorney or a mediator. Don't dig in your heels and insist on something you haven't fully thought through. You may be breaking ground on what later turns out to be your own emotional grave.