I think both are totally fine watches from two brands that can roughly be placed on the same level, so you can't go wrong with either....The *picture* of the JLC is nicer though, so if confirmed in reality, I'd probably pick the JLC (on your behalf :-)
Both are well respected and come from a strong pedigree. If you were going out to buy a time and date only watch and these two were your choice which one would you walk out with? Photos courtesy of the web. ...
...I've always thought that IWC were a bit rougher...not as well finished. And the modern IWCs are just too thick. Of these choices, I like the numerals compared to the markers.