I think you meant to say "buick lucerne".
Well, for one, the Buick is clearly sexier , the chrome trimmed sporty look is much more "modern" than the DTS' "deville" style chassis.
In the end, the DTS is probably going to be a better buy. Now the reason for that is that you are getting a V8 in pretty much the same car.
Honestly, both look amazing , but the DTS has more "luxury" features, not to mention that the style is also very "professional".
Im not sure if either have an automatic transmission that is mounted on the steering column , but that would actually be the decisive factor. Centrally mounted transmissions suck really badly.
Honestly though , this is a tough choice.