What is the ruling on one who revives Sunnahs but neglects obligations, and what is the ruling on one who performs obligations while neglecting other obligations and rights?

The most important thing for a Muslim after faith is to perform the obligatory duties (fara'id) enjoined by Allah Almighty. Indeed, focusing on supererogatory acts (nafilah) while neglecting obligatory duties indicates a deficiency in religious commitment and a deviation from wisdom. A Muslim must perform all the obligatory duties they are able to; they will be thanked and rewarded for what they have performed, and advised gently and kindly regarding what they have neglected. The caller to Islam (da'i) should be gentle in their call, and employ wisdom and good admonition.