I find the results for Dominicans of AncestryDNA aren't as precise as 23andme. The good news of AncestryDNA is that it's available in Spanish while 23andme is in English only.
23andme gets down to the provincial level.
AncestryDNA gets down to the national level and then a very general region. This is the equivalence of someone is looking for someone else and the only peculiarity they know is that the person is East Asian... in a place where most people are East Asian. Gee, thanks for the help. We will definitely find the person in no time.
Another reason I think 23andme is more precise than AncestryDNA is due to the Amerindian DNA.
AncestryDNA appears to not be able (or doesn't want to) pinpoint with greater precision which country your Amerindian DNA matches more. While the Tainos were one and the same (and the Caribs were not a genetically different people from the Tainos, they simply had a different culture and their name actually derives from cannibal for a very particular -and nasty- reason) not only islandwide but in the entire archipielago, they are able to pinpoint in what geographic area this DNA has been for the longest time. Otherwise, they wouldn't be able to differentiate the Amerindian DNA from most of the Caribbean islands and that is not the case. They do keep both countries shaded in different colors and the one with whom you match is circled by them.
Yet, 23andme is able to do that. I bet with Haitians that have some Amerindian, Haiti will be the highlighted country.
I also find there are more matches in 23andme than in AncestryDNA. Despite AncestryDNA has a bigger database, it's greater precision and the larger matches for Dominicans might make 23andme a better option for now. In 23andme some matches appeared out of nowhere of some people I grew up with and never occurred to me we might be distantly related. I have yet to see that in AncestryDNA. The DR is small and unimportant enough that for both to zero in on it is evidence both are accurate enough, but I think 23andme goes a bit further.
With that said, it's known that 23andme is slightly stronger than AncestryDNA when it comes to ancestry, while AncestryDNA is stronger for researching matches and official documents for building a family tree. I find for Dominicans 23andme is simply better on this front. The researching official documents part of AncestryDNA is only good if your family has been in the USA for many generations, as the official documents they do have are all from the USA, from what I can tell. They have no official documents after the country was created and in colonial times for the DR. Dominican documents do exist, AncestryDNA simply don't have access to them.
Lastly, both have historical sketches of the DR. AncestryDNA is more extensive than 23andme. Both are full of errors and is very evident whomever wrote them see things through a USA lense. At the very least, the people that write these things should be from the country it's referring. It's noted neither are claiming to be excellent sources of historical background of any place.
23andme gets down to the provincial level.

AncestryDNA gets down to the national level and then a very general region. This is the equivalence of someone is looking for someone else and the only peculiarity they know is that the person is East Asian... in a place where most people are East Asian. Gee, thanks for the help. We will definitely find the person in no time.

Another reason I think 23andme is more precise than AncestryDNA is due to the Amerindian DNA.
AncestryDNA appears to not be able (or doesn't want to) pinpoint with greater precision which country your Amerindian DNA matches more. While the Tainos were one and the same (and the Caribs were not a genetically different people from the Tainos, they simply had a different culture and their name actually derives from cannibal for a very particular -and nasty- reason) not only islandwide but in the entire archipielago, they are able to pinpoint in what geographic area this DNA has been for the longest time. Otherwise, they wouldn't be able to differentiate the Amerindian DNA from most of the Caribbean islands and that is not the case. They do keep both countries shaded in different colors and the one with whom you match is circled by them.

Yet, 23andme is able to do that. I bet with Haitians that have some Amerindian, Haiti will be the highlighted country.

I also find there are more matches in 23andme than in AncestryDNA. Despite AncestryDNA has a bigger database, it's greater precision and the larger matches for Dominicans might make 23andme a better option for now. In 23andme some matches appeared out of nowhere of some people I grew up with and never occurred to me we might be distantly related. I have yet to see that in AncestryDNA. The DR is small and unimportant enough that for both to zero in on it is evidence both are accurate enough, but I think 23andme goes a bit further.
With that said, it's known that 23andme is slightly stronger than AncestryDNA when it comes to ancestry, while AncestryDNA is stronger for researching matches and official documents for building a family tree. I find for Dominicans 23andme is simply better on this front. The researching official documents part of AncestryDNA is only good if your family has been in the USA for many generations, as the official documents they do have are all from the USA, from what I can tell. They have no official documents after the country was created and in colonial times for the DR. Dominican documents do exist, AncestryDNA simply don't have access to them.
Lastly, both have historical sketches of the DR. AncestryDNA is more extensive than 23andme. Both are full of errors and is very evident whomever wrote them see things through a USA lense. At the very least, the people that write these things should be from the country it's referring. It's noted neither are claiming to be excellent sources of historical background of any place.