Wow everyone is on a DX7 kick lately.
Ironic, analog makes a comeback and now so does FM.
Anyway having owned DX7 original DX7IID DX7IIFD without a doubt ....DX7IIFD.
Reasons are, original is mono (not necessarily a bad thing), the LCD is harder to edit because there is less characters, DX7IIFD does dual layer patches, unison. And more I am forgetting. There was already a thread recently on all this if you "do a search". Literally like a week a go a thread was going, no joke. No seriously do a search this was discussed with all the reasons.
The original does sound very slightly more gritty though.
If you use a software editor then the LCD doesn't matter.