My vote went to Joker: Enabled and 1v1 or 1v1v1
Joker to me reduces the randomness of the game, allowing you to take bad cards and by expending effort making them good.
It also allows for mind games using the numbers leading up to 90.
Joker to me is a fundamental part of making the game interesting.
Personally I think in a ranked ladder scenario (Arena mode) you shouldn't have to rely on a potentially dud teammate (or two of them!) in a game that shouldn't have communication; it should be entirely up to you. I am strongly in favour of individual play only -- i.e. I think 1v1 is the winning player count.
That being said I think 1v1v1 would be an interesting change, but it's a very soft vote towards it; I don't really think it'd be good in Arena mode, as you will sometime need to rely on an opponent to block. I also think when there's two people able to block you as opposed to one it's much easier to stalemate; and I don't think ties are handled well in Arena mode (This is a gripe with the ranking system, not the game -- It's my opinion that if you're bronze and you manage to tie against a platinum player surely that means you're on equal footing you should gain rank to move towards your ranks equalising?!)
I only voted for 1v1v1 because I think it'd be an interesting experiment to see under the lens of competitive play; and the only way to really make that happen would be to have it swapped to that config for a season; not because I think it's the best option for Arena mode.