Gardyloo has already pointed out the main differences between the two tickets - generally, you can get much more miles out of a OW Explorer than a GlobEx but you give up the ability to use certain non-OW airlines.

I'd start by asking myself "where do we (think) we want to go"? For the OW Explorer, it's based on 6 continents - Australasia, North America, South America, Asia, Europe and Africa. Starting in Oz, you have to do at least 4 continents (the usual ones being Australasia, Asia, Europe and NA).

Are you intending to fly economy (cheap <relatively> from Oz) or business or first (much more expensive from Oz compared with starting in some other places).

Do you want to go all the way round the world or would a Circle Pacific ticket, covering Australasia, Asia and NA work (i.e., no Europe)?

So many questions, no answers....

Give us some thoughts on places you want to go and the group can help from there ...