Depends on the scenario...
First off, outcalls by most SP's tend to be more expensive then seeing the same SP as an incall. No doubt that is because with an incall the SP can see another client immediately, where as an outcall they must spend the time getting to your outcall location and then returning or moving on to their next appointment.
Second, as so many TERBites seem to be engrossed in costs, if you are getting a hotel room for your outcall then it is going to cost you anywhere from $60 (day rate) to $150 for a decent hotel/motel. Add in the additional cost of the outcall appointment and you are looking at a difference of $100 to $200. So outcalls are more expensive.
The problem I have with incalls (unless SP is using a hotel room) is that I have been to a bunch of incall locations over the years where they are messy, dirty, smelly, etc. I know that I am not planning on spending the night, but in some cases I have taken one look at the bathroom and I just want to leave. No matter how attractive or "high mileage" the SP is. That being said, incalls tend to be less expensive.
That's my view. Since I am not made of money, I have to balance off the various factors and determine whether I want to spend the money and see the lady as an outcall or take the chance that her incall is not a nightmare.