I'm a fan of Alexander. He is good in the mid tiers of PVP and he is great for farming gold and 3* evolution shards in Number of the Beast mission.
Like most characters his strength really depends on who you team him up with.
Depending on your play style and patience level (and luck) it's good to remember that NF seems to run regular events that build up to trade in for random Liliths.
And also don't forget that NF indicated the Gods of Egypt will be available for an undisclosed amount of FC after the events are over. That might also be something worth saving up for.