It's a bit like saying do you prefer a 24oz claw hammer or an 8oz warrington hammer. Sure, there's plenty of overlap between them, but there are times when one is obviously a better choice than the other.
If I'm making cabinet furniture from veneered sheet goods (and I'm talking pretty upmarket items using saw cut veneers) then I'd tend to use biscuits more than dominos. A domino will often cause some localised swelling in the component, which on occasions can telegraph through the veneer surface. Another example might be fitting a drawer divider, too many dominos and you can find that your previously piston fit drawer is starting to bind, and by this stage you really don't want to be sanding that back with 80 grit on a veneered surface that you can barely reach deep in the bowels of a cabinet. These are the occasions when a good quality biscuit jointer really earns its keep in your workshop.
On the other hand, if you're mainly using solid timber construction, then a Domino, or traditionally cut M&T joints, will normally be what you'd choose. But even with solid wood there can be exceptions. The fashion is moving towards thinner and thinner legs, there are occasions when jointing the apron to the legs that two stacked biscuits makes more sense than dominos. The purists will squeal, but with a side table leg that has a straight taper from 28mm down to 15mm, plus with veneered "socks" at the feet further nibbling away at the integrity of the legs, the truth is that it's not going to be a particularly robust piece of furniture anyway, so stacked biscuits probably aren't the weakest link in that particular piece of furniture.
One other thing I don't like about Dominos, you have plenty of choice in the thickness and the length of the dominos, but virtually no choice in the width. Consequently you end up designing your furniture to fit domino dimensions, which quickly looks really "samey". Sure, you can extend the mortice width and machine up your own loose tenons (which I do all the time), but then you're just using the domino as a portable morticing machine and you've lost all the cost saving efficiencies.
Just my 2p's worth.