At the end of the day, IF is CICO (if you’re just considering weight loss). As long as you’re ingesting fewer calories than you’re burning in a day, it doesn’t matter which you do. Do whichever you can stick with and gets you the results you want.
Where you might get more benefit from 18:6 or 20:4 is with autophagy, a process that comes from longer fasting (usually more than 16 hours). If your goal is to engage those mechanisms, 18:6+ would be what you want.