For reference my B20V is basically stock. It's a B20Z2 block with a GSR head that was milled a bit a few years ago. It also has stock dual valve springs for both the intake and exhaust.

Any time I drive the car and need to start it back up while it's warm, it cranks really slowly. The battery is a brand new duralast. I had autozone test the battery, starter and alternator and all is good according to them. I'm assuming I need a better battery? If so, any recommendations?

Here's a link showing a video of a warm start and also a couple pictures of the battery: https://imgur.com/a/Rp29vza

 

use a multimeter to test the voltage readings of the battery with the car on....and off.
Off -- should read around 12.4 and up
On -- should be at least 14.1 and up
Watch the meter to see if voltage drops once the car is up to temp

 

That's basically what I had while the car was already warm. ~12v and up while off, 10v while it was cranking slowly and 14v while running.

 

sounds like you have a failing alternator. Get a reputable one, whether it's reman, used or new. Make sure it's the correct type as well.....OBD1 or 2. The connection plugs are different.