The BBC did a documentary in January - The Truth About Looking Good - that dispelled a lot of make up myths. I've just checked but, unfortunately, it's not on iPlayer any more.
It was a real eye opener and, as a friend of mine who works in marketing said, make up is all about selling hope. I can't help but feel we're being duped.
I can't remember if they mentioned concealers on the BBC programme, but the foundation that came out best was L'Oreal True Match - it's about £10 in Boots and Superdrug. It's brilliant. My local Boots has really good staff on the make up/perfume counter and helped me get the correct shade.
I treated myself to some LLF make up and, whilst it's lovely, I don't think there's any real difference from the L'Oreal foundation. I apologise to LLF but it's my experience.
I find the concealer sits in my wrinkles (I don't have many), despite following the LLF video tutorials step by step and using all the products recommended. Now I use it to cover thread veins, rather than under my eyes, so it's not wasted.
My DIL uses Boots Collection Lasting Perfection Concealer, £4.19, which comes in 6 shades. I tried hers and it's brilliant on my skin. Finally I've found a product that works for me.
Good luck with your quest!