Personally I prefer a keyboard with a gentle curve rather than an actual split - the old Microsoft Comfort Curve 2000 was my favourite for many years, but mine have all failed with membrane issues now.

I'm probably going to end up building a custom board with the features I want (gentle curve, ISO layout, nice switches) since what I want doesn't seem to be available off-the-peg. (The X-Bows keyboards are quite nice, but ANSI-only - I've done enough programming to have learned that I'm not prepared to compromise on the position of "\"!)