Hi AS,
My nails are thin and weak,split easily and flake etc.I started using opi nail envy and avoplex oil about 5 months ago and my nails are the best they have ever been.I am managing to keep the length and they do not break nearly as easily as they used to,they feel so much stronger too.
As for the polishes........as yet I have not tried the opi colours but by all accounts they are good,I have used nails inc though,and whilst I like the colours I do find that they peel and chip quite easily,sometimes I can peel a whole nail colour off in one fell swoop!!! That may just be me though.
LD I haven't tried either so no help from me there.
I got a virgin vie nail colour from their website in clearance and I found that it went on really smooth and lasted well,though the colour range is nowhere near as extensive as opi,nails inc or LD.