If you were DCAing into gold and silver weekly for 20+ years which ETF would you trust?

I’m trying to choose a simple long term setup for gold and silver using ETFs and would appreciate some perspectives.

The plan is to dollar cost average a small amount every week and hold for 20 plus years with no trading or market timing. This is meant to be a buy and forget hedge alongside equities.

For gold, I’m specifically looking at GLD versus IAU. For silver, I’m looking at SLV versus SLVR.

I’m mainly concerned with long term reliability, expense ratios, liquidity, tracking accuracy, and any structural risks that could matter over decades.

For someone taking a steady weekly DCA approach over a very long time horizon, which gold ETF and which silver ETF would you choose and why?