Assuming the airport is MCO and the hotel is in the WDW area but not a Disney resort, the answer depends mostly on how many people are being transported and their ages.
For three or fewer people, a Mears shared ride shuttle at $30 per adult and $24 per child for a round trip (plus tip) is going to be the cheapest.
A cab is going to be $100-$120 plus tip round trip, so that will be about the same price as Mears once you hit four people and if you have five or six in a van cab it winds up being a better cost per person than Mears. Town car service for up to four people will wind up running about $120 plus tip, so about the same as a taxi for four people. Most of the transportation companies, including
FL Tours who sponsors this board, will be within $5 of that either way.
A van for up to 10 people is closer to $135 plus tip, so at five-six people it's a little more per person than a van cab. Once you hit seven, it's a better deal because you'd have to get two cabs in most cases at double the cost.
If you are staying at a Disney-owned resort, DME obviously is the cheapest as it is $0 out-of-pocket (other than a tip for the driver if they handle any bags for you).