cutex for weak nails is very good. It is one of the cheapest, yet also good for the nails. And it really works while some products are hard work. It wins hands down. (sorry!)
I don't wear nail varnish anymore. I tried all the various types and never saw any difference...except that the pricey ones did a more complete job of removing the varnish. Some own brands did nothing. Boots own was OK.
Looking at the answers on this post I wish we had the old system whereby I could rate the answers
Instead I give special 'shout out' to Svejk and Gavmacp