Leaders should be drafted first so that you know the general idea of the deck you are going to make. That's how I see it but I might be wrong.
If you pick Eithne you will give priority to special cards. If you played the SK leader that sends 3 cards to the graveyard you will give priority to resurrection cards.
Same with queen arachas, it's usable only in consume decks.
Emyr is also useless unless you have runestones/silvers of quality.
Moorvan can only be used with the reveal mechanic.
Henselt is 100% useless too if you can't pull Kaedweni stuff.
Half of the leaders are currently really bad if you can't play around them.
I've also noticed a lot of stuff that is kind of unplayable/should be changed in arena.
Consume cards for example are really bad because usually you only get their base value instead of the usual combo value when they synergize well.
Most cards that "invoke" all their copies from the deck are also kinda bad, I mean, at most you will get 2 equal cards and even that is really hard.
Ciri: Nova is completely useless too.
I know the card pool is really low right now and giving more than 4 cards to choose from might end up giving too optimal decks.
My recommendation is that you should be given the option to have 35 picks, then make a deck with 25 cards (or more).
There's a lot of annoying situations were you pick for example Ithlinne as a gold on the 3 first picks because you love the card, then don't get a single Spell or Weather bronze card for the rest of the game. You expect to try out sweet stuff like playing a double full moon on a deck full of beasts, or double bad moon on opponents row, but most of the time you can't play the card because too many golds/silvers.
You could also limit the amount of Golds/Silvers in the deck. From the 35 picks make 6 guaranteed gold picks, 10 guaranteed silver picks and make the rest bronze picks. You should have plenty of stuff to play from without breaking the game. I've played Royal Decree into Dandelion
oet into Royal Decree into Vilgefortz into Aglaïs into opponents runestone into Burza into my own Runestone from the deck etc, making some really sick plays.
I also think the amount of golds should be limited. I have a lot of scraps to play arena (around 5.000) and I rate higher to have fun than sticking with a deck with 2-3 dead cards. Yesterday I conceded 3 straight decks after I saw they werent optimal, then the fourth 4 had 10 golds, 10 silvers and 5 bronzes, full of value and fun plays (Francesca into Imlerith:Sabbath, etc...).
You don't lose that much value from conceding the first game, it's usually a barrel + 30 meterorite powder from 150 scraps in exchange for not wasting 2 hours with a subpar deck.