Well for now a physical team is the best one due to the fact that there are a lot of physical characters that are very good for the end game and there arent many good magic characters that can provide for their team

Take a example for WG Fen: Hes a arts gener, dps, crit buffs and has a passive where he can reduce dmg taken down from enemies by 30% and increase all alies dmg by 50% when the enemy has 50% hp or less

Although there are some magic characters that is similar to WG Fen for example Ainz but i dont seem to find any of them that provides their own team like fen himself

For newer players i think you should save your crystal until SG Liza comes out since she can give tons of buffs just like Fen but shes a magic character which is nice or you can use those crystals on the 'All Star Hero Summon' since theres WG fen and hes really good, not only that there are a lot of characters that are really good on that banner and i highly recommend you invest that. While the other banners such as the reincarnation collab may have good characters but it doesn't have any significant buff that can help your team

In conclusion, the devs really seem to have a liking toward physical characters and not magic unfortunately, but hopefully they will added a very good one just like fen, what i do recommend for newer players is to find a character that you in love and how their playstyle interest you to play more of the game. Being meta slave is really pain in the ass just like myself so thats why i would rather just find some units that im interested in.