No one can tell you what is right for you. Your options are:
Roll over into IRA = keep the tax deferment, allow it to grow for retirement. IRAs have certain flexibilities that 401(k) plans don't have as far as early or hardship withdrawals are concerned if you need that down the road, but they often have higher fees. Decide on an IRA provider first and then do a direct institutional transfer, so the money never touches your hands.
Or leave the money alone = you can usually leave it in the current 401(k) unless your employer forces you to take it out. It's a good way to save for retirement and the 401(k) plan usually has lower fees but a more limited set of investment options. If you are satisfied with the investment options, you can leave the money alone.
Or, transfer the money into a qualified retirement plan (401k, 403b, 457) at your new job. Again, do a direct transfer, don't get a check.
Or withdraw the money. You will pay income tax plus a 10% penalty plus state tax, so you could easily owe 40% or more in taxes.
Or, convert the money to a Roth IRA. You pay the regular income tax (same as you would pay if you take the cash) but not the penalty, and the money grows to retirement. In a Roth IRA, the money won't be taxed when you withdraw it in retirement, which is nice.
Understand that if you are 40 years old, $50,000 left alone in a tax deferred plan will grow to $300,000 by age 70. Or take it out and have $30,000 to spend now and then it's gone.
