HP ProDesk 600 g1 sff Vs 400 g2.5 sff

[Disturb1]

I am trying to choose between these two models I have both and which ever one I go with I will used the i5 that I have on hand as well as the 16 gigs of ram

two sticks of 8 in the 400 g2.5

four sticks of 4 in the 600 g1

( I know I will need a low profile decent video down the road ) 
my big problem is I can seem the find any in which mother board is better nether seem to have raid built in to the bios another card to add as well 

the hp ProDesk 600 g1 does have a little more room for expansion cards

but does anyone know anything I am missing that is the oh definitely use this one ?  

Help please