In the past I have used regular pex for water.. I am doing a radiant floor project now and for the floor they sold me pex-al-pex. However I think that mas more to do with the fact that pex al pex is air/gas tight. You want that when you are recirculating the same water.
But for regular potable water I just use regular pex.
when using a manafold I do all home runs.. 3/8 toilets and bath sinks. 1/2" for showers, and hose bibs.