Diamond/chu is out of the question because modo has to tank mostly with its HP after nimble spirit is raped. ( diamond doesnt give enough boost for it to be reasonable as a choice )
If the rumours about bugged NS in regenesis are true, STJ/BG are both equally good options ( rumour regarding NS is that in regen it also absorbs white dmg)
But id still go for BG anyday, 300k+ hp is a must, only if youre voida/celan, you should go for high SP.