fan ovens are supposed to have a very even heat, so all the shelves cook at the same rate. Gas ovens seem to heat up very quickly, but having lived with all combos of gas and electric hob and oven, I'd go for gas hobs and fan oven every time (never had induction hob tho)
I wouldn't have fan-only as the temperature is the same throughout, so you can't cook things needing different temperatures at the same time. Go for a multi-function one that has both fan and standard cooking, plus grill if you need it.
I've got an AEG fan/standard/grill oven - it's superb. I never use the standard cooking to be honest. It's always quicker than the cooking instructions for fan ovens so I did get caught out at first but no problem now I know.