Mes podcasts préfèreérés.

"préfère" is a present form
The past participle used as an adjective is "préférÉ", agreeing in the plural with "podcasts"

Pour apprendre le français, j'aime les podcasts d'eEasy fFrench et cCoffee bBreak : ils sont très naturellements et très faciles.

Podcast capitalization rules can be quite tricky, but with English names, the English rules would apply
At least a semicolon to give an example or complement to a main sentence
"naturel" is an adjective, "naturellement" an adverb
Plural agreement again => facileS

En général, j'aime écouter les podcasts des Crimes et documentairesocumentaires ou parlant de crimes.

You need an "about" here, so "parlant de" would work