I find this a very peculiar comparison between the 2. One is a very sporty and desirable sport watch(JLC) and the other, a rather elegant and versatile watch (IWC).
I hope your decision is driven by how it feels when they sit on your wrist and not by the maintenance costs. Both are manufacturer's calibre and are comparable when there's a need for full service.
In any case, can't go wrong with either one of them. However, I'd personally settle for a master control Memovox instead, if JLC is my path, as something that can stand the test of time. The Amvox 1 is easily, how should I say,... forgettable... sorry, just my 2 cents...