I use a sykes pickavant flaremaster 2 kit.
It's brilliant for flaring on-car & never let me down.
I've never had any luck with the cheaper hand-held flaring tools when it comes to flaring steel pipes & for me, never produced a really good flare.
Not cheap though unfortunately, an example of the full kit here.....you may find it cheaper elsewhere:
https://www.primetools.co.uk/product...ring-tool-kit/