I've used Ibex and Happy Limo... to tell the truth, I wouldn't use Happy Limo again if THEY paid ME to travel with them. Though I had told them in advance that I would be making a grocery stop, it was a big deal and obviously an inconvenience to the driver. On our return trip to MCO, they were very late in picking us up. Even though they provided us with an "upgraded" car for the return trip, it did not impress me. I would rather have a courteous, on-time driver than a flashy car.
On the other hand, we did really like Ibex but being a small company, their prices are now a bit out of my range.