IN a word - PRODUCERS. These are the guys with revenue, who will stand to gain from the coming frothy whip-saw.
Beyond that, the rising tide will float all boats but there may be some advantage to pile in on the common ones like First Majestic and Mux.
SLV has been mentioned too although PSLV is the better etf bet.
The problem is, there aren't that many primary silver producers. Most of it is coming as a by-product of copper and gold.
Even HL long famed for it's silver output, gets most of their revenue from gold now.
GORO put out almost 2 million ounces of silver in 2019 (along with gold, copper, lead, and zinc) but I haven't really looked at them that closely since the china virus hit. GORO probably has the best leverage right now due to the spin-off. GL !!!