+1 on the Subtank Mini. It's 4.5ml and a solid flavor and vapor volume performer. Kanger's OCC line of stock coils cover the whole gamut of options. Ceramic, SS, Ni, Clapton.
There's also a top-fill version called the Toptank. 4ml, though.
Thank you all for your replies. What if I update my requirements to include two more
1) TC coils
2) More than 3-4 ml
3) Nice range of coils
4) RBA coil
5) Top airflow
Is there a tank to cover all five?