If you meet the eligibility requirements for both Chapter 7 and Chapter 13 bankruptcy, then you may choose which type to file. Otherwise, you may not have a choice.
Those with an income higher than the median income for a similarly sized family are not eligible for Chapter 7 if they would be able to repay some of their unsecured debt within five years. To be eligible for Chapter 13, you must not exceed a certain level of debt (see Individual Debt Adjustment for current limits). If you don’t meet these requirements, then Chapter 13 bankruptcy is not available to you.
Usually, those who have a choice in the matter go with Chapter 7 bankruptcy, since they may be able to have all of their debts discharged (besides the debt covered by the proceeds of liquidated property). Chapter 7 also can be a much faster process than Chapter 13. However, Chapter 13 may be the best option for those who have adequate income and substantial assets.