My vitamin d was 24 last time checked. should i still take a d3 supplement and if so, is there a certain brand that's best?

Yes, however...: Normal levels of Vit D are 30-100, though 50-80 is the optimal level. Achieving good levels helps prevent heart disease, cancer, autoimmune disease, infections etc. In fall & winter all adults should take 5-8000 iu/day. In spring and summer spending about 20 min. in mid-day sun without sunscreen can give enough D but if you don't do that take year-round. Best with K. Many good brands- see comment: