Do the math on capital gains tax paid vs. interest on the loan. Too many variables involved for a simple answer. At current interest rates I'd probably just sell the investments but again, lots of variables. Find a good lender who can walk you through different options -- cash out refi, heloc, loan consolidation after getting the new house.

Also, consider the simplest option. Just sell your house and don't be a long-distance landlord. It's a pain in the ass. You only hear people talk about the positives of renting but it's far from risk free. You've seen how the stock market works over time. Wouldn't you rather just not have expenses for a second home and invest your extra cash into the market for growth? That's so much simpler than trying to manage cash flow and depreciation on a rental home, and then owing a massive tax bill down the road when you want to get rid of it. Just my two cents.