Vavau or Haapai

I'm currently planning a trip to Tonga - I will be there for 12 days and originally planned on spending 3-4 days each on Eua, Vava'u and Haapai - however because the ferry is irregular/potentially unreliable I think I will have to get around by plane so have decided that I am possibly better to just visit Vava'u or Ha'apai (because of cost) - has anyone dived in both these places - is one significantly better than the other - it looks like Vava'u may have better diving but it is a lot more expensive to get to and it looks like the diving there might be more expensive - is it worth the extra cost - which will mean I will be able to dive less!?

Also any other tips/accom recommendations for any of the locations would be greatly appreciated!

Go for Haapai, it is cheaper both to get to and to stay.
And the coral there is still very nice.
I stayed at Langilangi's Guesthouse in the main town (where you have to stay if you want to dive and stay cheaply), which is basic but very friendly, and was the cheapest accommodation I've come across in Tonga at TOP15 for a room.

Vavau has much more interesting scenery, but you should see nice enough scenery of the hilly kind on Eua.

I highly recommend Ha'apai!
Amazing beaches, amazing place and super laid back

Jon

Ha'apai by far stay at Matafonua Lodge great diving great food and killer beaches