If you want to print white on dark t-shirts,
DTG is the only option.
DTG can work, there are people on this forum who will testify to that, but there can be a lot more barriers to entry. Some people have experienced maintenance issues, and you have to have realistic expectations. White ink is still a work in progress, and not all
DTG printers are ideally suited to printing it.
Sublimation is another option. That uses transfers and an Epson or Ricoh printer. You can't print on dark shirts and you can't print white, but there are generally less maintenance issues and it might be easier to get started.
Depending on what it is you want to do, either option might be right for you. The one thing you need to do is get a realistic picture of what is involved.
Heat transfer v.s. Direct to garment 
