The downside of HDD is once it is full you have to delete of download to keep working. Not so good in the middle of your overseas holiday. You can always slip in another card if you can afford enough of them.
Don't underestimate the old DV tape format. Both the cameras and tapes are very cheap. Remember it is a digital format does not suffer from noise like an analog tape format.
Dollar for dollar the picture quailty is better than either HDD or card.
Both HDD and Card types use MPEG compression which can result in strange visual artefacts. Try panning at various speeds across a repeating pattern of vertical lines such as a paling fence or a row of palm trees.
I would expect the card to be the most robust as the HDD is a precision mechanical device. Presumably they cusion them fairly well.
Cards will continue to get cheaper. Make sure the camera has the ability to read higher much capacity than are currently available.