Didn't get a single baby turtle/teenage turtle/alvida/coby/Gaimon/Sea King since the update. I also failed a ship upgrade and skill books didn't give me any skill up.
Updated Tier List
Shanks/Ace/Nico Robin/Vivi/Zeff/Arlong are all pretty good starter units, but only Shanks, Ace and Robin are exclusive to Rare Summon.
--- Disclaimer: In the rest of this post I'm assuming that the Arlington you pulled is an Arlong ---
4* Arlong is the most used leader right now because he has great stats and it's pretty easy to build a crew around him. For the rest, only Robin is pullable in 5* form and the 4* forms have just OK stats and evolving them can be a pain.
If you want to re-roll, you can save the account for 7 days by going to "others" > "issue password". You can also try and trade your account on /r/OnePieceTC, you can often find people trading Ace/Shanks/Nico accounts for 4* Arlong.