It really depends on your taste and pocket
Ajwa is famous for it medicinal properties as mentioned in Ahadith, Khalid Bin Walid's heart problem was treated by Prophet PBUH with Ajwa, less sweet and thick seed.
Mabroom very small seed bit tough on the teeth, very sweet.
Dhaki from (Dera Ismail Khan) if someone can sell you the original pot prepared (water pitcher) it is heavenly
A friend send me few kilogram every year its called Iraqi, large in size, average seed and less sweet in taste.
Begum Jangi from Makran area is also very good, an interesting fact is that Mabroom and Ajwa are now being grown in Pakistan particularly jhang, bhakkar area. I also donate Ajwa and Mabroom plants every year.