The Arena gets really exciting when there is a Leader Card and especially the 1000-gemstake. People notice and get excited.
Otherwise beyond this, with the mounds of coins, chests (with 99.8% junk inside), exp that gives 0.0001%, and the credit stakes that are laughably useless beyond belief ..... if it's not gems, we yawn. They're not even worth the click to attack your neighbor.
Most people won't even jump for the leader cards. (not worth the 150gems to transfer).

What I'd like to see is some added hope & excitement to the arena. (but making this rare so it's not too powerful).
Here are some added things one could also put in as arena-stakes...
-- You already have Leader cards, why not add Gold and Purple cards? and Blue cards? (caution: make sure they are redeemed as heroes the player has already unlocked -- newbies getting Pompey and Genghis can be very bad). Gold hero giving grand announcement.
-- Blue Stars and Purple Stars (which was brought up in an earlier thread). Purple star giving grand announcement
-- 100 casino chips (1 spin), or 1000 chips for grand announcement
-- maze tokens (1, or 10 for grand announcement)
-- lvl1, 2, 3 chips

... basically having almost every single thing that exists in the casino (but not skill scroll or 20,000 gems) to be included as an arena stake (like the existing 1000gems and leader card).

Is this necessary? no. But it will certainly increase the *excitement* on that Arena button we always see and don't bother to click.