The USD . Also it is likely , witness recent supporting evidence , that Short emerging markets, short emerging market currencies, short commodities will do well. Theory says (i think) that anything borrowed, funded and leverd in USD (short USD) will experience currency risk. They are effectively long a local currency and short USD so that spread will move against them and net with any capital gains of the asset. If both the asset and the currency move against them "the trade" can be unwound further driving up US treasury rates, USD and driving down some of the previously mentioned assets. Small exits in a crowded trade. You definetly want to pay back borrowed money at a lower value. This all assumes forex flows driven by interest rate differentials prevail. I read that these differentials is what is behind these trillions.
Might be better to ask what will do poorly as there seem to be more to select from.
Inverse etfs are a plenty these days if not able to short things.