Given IG's ambitions to be a prominent carrier in Italy and Europe (or rather QR' ambition), I think it would rather pursue a full membership in Oneworld rather than being a Connecting partner or affiliate member.

Meanwhile I think EI will be best suited to be Oneworld Connect partner given it (or IAG) seems unwilling to pursue a full membership due to high costs. EI being a Connect partner would be beneficial to its global outreach and of course Oneworld while procedures for a full membership will not be needed to be carried out.