The flexibility to be able to change easily from one platform/technology to another without having huge capital investments in place is very useful for us as we are constantly evolving our technology stack, so being flexible with this aspect has been key! There's nothing I dislike about dayhoff at present time but if there was something that would help me improve my experience it could possibly be more detailed training material regarding each product they offer - especially their Cloud offerings (which have received some attention over recent years).
We use D-dayff primarily because its quick deployment capabilities which makes life easier when you need an immediate solution or working prototype quickly.