I am devising a plan to make a homemade LED panel for film/photography with diffusers and such and im wondering whether anybody has recomendations of specific LEDs as there are so many to choose from online. I am planning to attach about 25-50 in series in an array without mains power (only battery powered).

 

Here's a whole bunch of 'em.

 

50 white LEDs in series will need at least 160 volts DC.

Were you looking for name brand LEDs or something a little cheaper?
What kind of total wattage were you looking for?
Did you want to use strips or discrete?
Do you want surface mount or maybe something a little easier to deal with such as a COB mounted on a spreader?

Flesh out your concept a little further.

 

I have used: Cree XLamp, XM-L RGBW @ today about US $3.29. Mounted on 20 mm star heat sink. Max. power 12W & 1 A. From ebay, about 2015.
Vf @ 350 mA, R = 2.25 V, G = 3.3 V, B = 3.1 V , White = 3.1 V . With 12 V battery drain about 2.8 A, one color at a time, 350 mA.

 

I like Neopixels. They may not be industrial flood lights but they are pretty bright and they don’t need 160 volts. 5 volts, 10 amps will run a bunch of them.
I had to turn them down on my Graphic equalizer club lighting in an infinity mirror because they were too bright.

https://www.amazon.com/ALITOVE-Individual-Addressable-Programmable-Non-Waterproof/dp/B01MG49QKD/ref=sr_1_37?hvadid=78408975146831&hvbmt=be&hvdev=c&hvqmt=e&keywords=neopixels&qid=1571133876&sr=8-37

https://cdn-learn.adafruit.com/downloads/pdf/adafruit-neopixel-uberguide.pdf