In his good news FanPost bucsfaninwa talked about
happy event Clint Robinson makes Jones expendable
But the prevailing wisdom is that Jones should be the starter. That Jones has major league experience is a plus, but Robinson appears to be a somewhat better hitter with a bit more power. In his two seasons in AAA Robinson hit for a batting average of 309, an on-base percentage of 396, and a slugging percentage of 493, giving him an OPS of 889. Jones had five! seasons in AAA with a slash line of 266/321/464 for an OPS of 785.
I'm going to ignore AA statistics, because Robinson played in a launching pad, and Jones didn't. Both played in fairly neutral AAA parks, Omaha for Robinson and Rochester and Indianapolis for Jones.
Neither is a particularly good first baseman. We can see that Jones has sub-par numbers in the majors, and Robinson's numbers look slightly worse than Jones's in the minors. For example Clint had a career fielding percentage of 0.986 at first and Garrett had 0.988. Neither of those compare well to what good fielders did in the minors, and Robinson really can't play anywhere but first.
I guess that's the deciding factor. Going with Clint leaves you much less flexible than going with Garrett and stashing Clint at Indy.