Spanish and Portuguese Speakers, What are the hardest and most complicated Verbs to Conjugate for you?

Hola/Olá, I'm not a Spanish and Portuguese speaker, but i have an interests in your languages, In Spanish and Portuguese there's so many Verb conjugations for each subject, time, mood, and so on. The verbs are also divided, Irregular and Regular. Regular verbs are easy because the conjugations doesn't change to much but the Irregular one could change drasticaly depending on the Which verb is it. My question. What are the Verbs that make you go "WTF" or "Why?" For how ridiculous the conjugations are.

Gracias/Obrigado