For sheerest coverage I opt for the trusty Maybelline Instant Anti-Age Concealer in Nude. It provides enough coverage and under eye brightness for a day to day basis. The sponge applicator makes it extremely easy to blend so its a perfect choice for rushed early mornings.
My slightly higher coverage option is the Une Skin Echo Concealer in E12. This has a very liquidy consistency which makes it very easy to blend with a brush or with fingers. When swatched it has some shimmer particles but when applied and blended the shimmer doesn't show through. To me this concealer is fairly fool proof as it gives a medium coverage and goes on very easily.
Finally, for my highest coverage choice I go for the Nars Radiant Creamy Concealer in Ginger. This is a much thicker formula which makes it extremely high coverage. Its slightly harder to blend out but with the Zoeva Concealer brush mentioned here I find it works beautifully and you only need a tiny amount so it will last for quite some time.
Whats your favourite concealer?