Gotham Knights Gear & Weapon spreadsheet (Credit: /u/frobones on Reddit)

https://docs.google.com/spreadsheets/d/1fVo0OH6ryQy5jZFwZ2y6Mtl985P9kQ01qkjzctw1-Xw/edit#gid=1415662473

This spreadsheet will show you which faction drops which type of suit or weapon, since all of the equipment have predetermined stats and passives you can look at which build you want to create for your character and hunt for those specific items.
Click the various tabs at the bottom of the spreadsheet to navigate to different pages for the info you're after.

Some notes about gear, power is not the be-all and end-all. Look for synergizing passives that fit your build or play style. Power is just the calculated value of the overall stats for a easy comparison between items.
Crafted epic and legendary gear can have a chance to upgrade further, giving more stats and is indicated by a icon with a gear and arrow up, next to the item name. (See here https://imgur.com/a/KoCx8vz )
Here is a comparison between two suits, the upgrade is only +11 power ( See here https://imgur.com/a/JNMzHFH ) though it is unconfirmed that once you've upgraded an item once, you can craft it again and it'll upgrade higher than previously.

Remember to un-equip mods when comparing items, since the game will show modified stats in comparison, thus invalidating it.

Post any additional info we could add here or questions, thanks for reading.