As jnharley said, depends on how much room you have. We have had Splindid combination/vented and now we have Splindid side-by-side vented.
Pros and cons to both systems. The combo unit can be nice because you can put a load in and forget about it, no switching from washer to dryer. But they don't take a very big load.
The stackable, or side-by-side units are nice because you can get bigger loads in.
We have stuck with the Splindid brand mainly due to their unmatched customer service record.