Colt, Ithaca, and Remington Rand are classics, and combined made up the vast majority of 1911A1 pistols produced during the war. I've always been partial to the Union Switch & Signal roll mark, and of course the unicorn of WWII 1911A1 pistols, Singer, of which I've only seen one (wasn't for sale).
Overall condition and matching original parts drive price more than anything, as well as whether or not it's been reworked post war, but rarity will be a big price factor for US&S pistols, and especially for Singer.
Published numbers of 1911A1 pistols produced during WWII...
Remington Rand - 878,000
Colt - 629,000
Ithaca - 335,000 - 340,000
US&S - 55,000
Singer - 500
Of course, anything to do with US military firearms is heavily debated. It's a hobby within a hobby for many.