The Uniswap liquidity token is essentially 50% ETH and 50% another token that does well while Uniswap volume outpaces volatility.
The two largest Uniswaps by ETH are DAI and MKR, so these would be good sources of collateral. It’s easy to oracle the value of uniswap liquidity tokens based on their underlying assets.
Uniswap MKR has 344 holders and a market cap of about $3.5mm
Uniswap DAI has 752 holders and a market cap of about $2.7mm.
Uniswap WETH never made sense to me but people still use it. 112 holders and a market cap of $2.5mm.
If we accept WBTC as collateral, the WBTC Uniswap would also be a good candidate, being 50% ETH and 50% BTC and having 55 holders and a market cap of $870k.