As a WHM, I'll go 44 SS + 31 PIE.

SS is a personal choice. For me DET - supposing you add 100 point on this stat, you gain like less than 60 healing points on a Cure II - is the most useless stat (even if 100 points DET gave 100 healing points on Cure II, it doesn't change anything when your cast doesn't save your target). Mainly I stand for SS for the GCD reduction and for the target switching that is faster.

And PIE because when you start to maximize SS, you begin to burst your MP at least 10% or 20% faster than any WHM without any SS gear.

So PIE is complementary to SS in this case.

Finnaly, on others pieces of stuff, if I can get some crit it's a bonus too. I think having a base crit can help, but not having too much for the reasons a lot of ppl explained earlier.