Here are a list of some handy stablecoin comparison charts.
Coincodex is probably the best on as it provides the ability to select up to 17 stablecoins and compare their value over the time frame of your choice. Each stablecoin can be toggled on or off as well which is very useful.
Longhash provides an interesting stablecoin health index as well as price charts for 5 stablecoins. Each stablecoin can be toggled on or off.
Stablecoins War shows the chart for 7 stablecoins but without the feature to select or unselect various stablecoins.