Appreciation vs. cash flow and market cycle

[Son N.]

Hello,

If you have a property with good cash flow (12% CoC) and also good "unrealized" appreciation (if sell now, after-tax gain is worth about 10 years of cash flow).

Would you sell it to realize gain now if you think RE is near the top of this cycle? Would you do a 1031 exchange (sell high, buy high, assuming you want to stay local and not consider out-of-area)? Or would you just sell it normally and pay long-term cap gain? 

Thanks for your thoughts