When comparing apples to apples, it's hard to beat the 5th wheel for price. Remember, with a 30' MH, you lose 5-7' at the front for the cockpit.
Set up time: It's really not much difference assuming you pull a car behind the MH.
Both drive very nicely assuming they are set up properly to begin with and properly maintained.
Storage is probably a wash.
Fuel costs: The MH figure 6-8mpg when traveling. 5th wheel 9-12mpg. You gain a bit of advantage with using a small car for local touring but unless you camp a long way from your desired location (not sure why you would do that with a home on wheels), it's really not much of a savings and comes at the cost of maintaining two drivetrains.
For full timing, I really don't see it as a big advantage to be able to get up and roam about while driving. We usually only travel a couple hours in a day and since we aren't in a hurry, it's not a big deal to stop if it's a longer run. I would suggest that any rig you buy is usable with the slides in. We don't normally put the slides out if we stop in a rest area for lunch.
To the new question: How big of a truck depends on how big of a 5th wheel. With our 28' model, a 3/4 ton truck does nicely. If you get up into the 40' models, a 1 ton dually may not be enough and you have to move up into medium duty trucks (I wouldn't recommend going that big anyway). Reality is you need to look at the weigh ratings and the weights of the 5th wheel (don't forget to check the tow ratings if you consider a MH).