In my opinion, the best vitamin D3 is that which you get from whole foods or that your body makes directly from the sun. Fish high in Omega 3s, such as Salmon (preferably wild, not farmed), Mackerel, and Sardines are great sources, as are eggs and porcini mushrooms. Sunlight exposure obviously carries risks, but is still a great option is used in moderation.
If you do supplement, the key is to stick with D3 (cholecalciferol), which is the only bioavailable form of Vitamin D. Most conventional supplements use Vitamin D2, which is poorly absorbed by the body and has shelf life issues. Any specific brand preference will probably come down to a taste preference, but ConsumerLab does provide independent quality testing of Vitamin D supplements to help you make your decision: https://www.consumerlab.com/reviews/Vitamin_D_Supplements/Vitamin_D/
Actually D2 is available only by prescription! And you definitely are NOT going to get what you need in vitamin d through your diet, even if you eat an entire fresh caught Salmon each and every day! I visited with Doctors from all over the world in San Diego last may and when asked about Vitamin d testing, not 1 single Dr said they had ever tested one human that was NOT deficient! We do not get enough sun anymore so now the majority of us are deficient! No ifs, ands, or buts about it! I personally prefer the same D3 used in most every clinical study from the past 10 years to the present and that is D3 from Bio-tech Pharmacal. Why? Because I know that studies conducted by Mayo Clinic, Cleveland Clinic, or Mount Sinai School of Medicine, just to name a few, insist on using the best available for their trials, and that is Bio-Tech's D3! So personally I do not give a rat's patootie about some laymanst "D3 review" ! I trust science and facts, and the scientists obviously prefer a product they KNOW is the best! http://www.biotechpharmacal.com/catalog/category/vitamin-d/