MoonSong
Rules-lawyering drama queen but not a munchkin
Honestly the first favoured soul was awful as a warrior, weapons did not provide anything worth using, and Greenflame Blade and Booming Blade we're better then using extra attack because the weapon choices we're so poor.
With Mage Armour, Green Flame and Booming Blade, and a Staff the new Favoured Soul is actually better in melee combat then a Old Favoured Soul armed with light armour, a spear, and extra attack. New Favoured Soul has +1 more AC, can use it's weapon as an implement to cast spells, +1 hp per level, and Favour of the Gods over the Old Favoured Soul. Either way if you wanted a good fighter, you need to dip into the fighter class for 1 level, which gets you all the good weapons, heavy armour, shields, second wind, a fighting style.
And the Quarter St
Green Flame Blade and Booming Blade are from SCAG. Remember the two-book rule, we cannot compare two things if we are including material from an extra book in the equation, because the designers absolutely won't take them into account for design purposes. If you have a favored soul -old or new- you cannot assume Green Flame Blade and Booming Blade. And even if you assume it, the old favored soul is proficient with more weapons anyway, so there are more chances to land both attacks. And the old favored soul can also take mage armor, in fact is more likely to afford it with the extra known spells. All the new one has is a measly +1 hp for combat.
Besides that, I've been playing an old Favored Soul for a while. And let me tell you, you don't need to be alpha striking to be a worthwhile melee character. All you need to do is contribute and avoid dying long enough to patch everybody at the end. I don't even wear armor or use mage armor and I've yet to be hurt enough to need rescuing. Even the party forgets sometimes that I'm a squishy.
Maybe the quarterstaff is so good that no other simple weapon is worth anything -but in that case, would it hurt to be proficient with other simple weapons in order to have more aesthetic options?-. But even then it pales in comparison to the psychological rush you get from using a spear. A staff is only a stick, a spear is the one universal weapon that connects you with all cultures and millions of souls over the eras. Can you throw a staff? can you dual wield staffs? Besides simple weapons also include the shortbow -the other universal weapon-, can you attack with your staff something more than 60 feet away?