TOEFL and IELTS both test candidates' English Proficiency. Both the exams are on the same level of difficulty. Read the following to choose a proper exam.
If you are applying for immigration then take IELTS General. Since it is easier than IELTS Academic and TOEFL.
Some universities demand only one score. If you are applying for a university then write the exam whose score the universities are accepting.
If Universities accepts both then consider the following factors:
You can take TOEFL if you are comfortable with American accents else if you are comfortable with European accents take IELTS.
TOEFL is relatively longer than IELTS. So if you are ok with a longer exam duration you can take TOEFL or else IELTS.