Mi-Fi Which to get

[techguyone]

I've started looking at Mi-Fi devices, probably from EE as their coverage is best, dos anyone have any experience with these things? from a quick look I can see that 'probably' the EE Osprey 2 Mini would be fine - I don't need a pay monthly option for my needs so the PAYG option might be better (3 GB over 90days)
I can't see however, how much extra GB's are to top up or how long they last for.

Or should I be looking at something completely different?