Ambeo
Speaking from a neutral standpoint i have used Ambeo and have to admit they have saved my skin when another operator pulled an aircraft on me. so perhaps my view maybe more bias than others.
Though i have not personally flown them i have arranged a multitude of flights with them and on every occasion i have always had a positive feedback from the passengers.
Some may say their weakness is that they are new to this industry and only have a small fleet but conversely i rather think this is to their advantage.
They understand that they have have to obtain market share not only by being competitive but also by offering a service to which i would say they are at the time i write this acheiveing very well.
The aircraft (Mustang) is an interesting little aircraft and is perfect for small trips
However, and i write this as passenger not as a pilot the mustang does have it's limitations. compared to the Bravo (NJE smallest cessna) it does not have a toilet at the rear and is not really suitable for 4 adults in the back.
Baggage space can also be a consideration but in my personal view and with any prejudice to any fractional scheme i would still take the smaller mustang of Ambeo than one aircraft which has no fixed abode to which you are commited to use for a said period of time (25hours or so).
After all with Ambeo or indeed any charter company if you didn't like the experiance you can use another company / model of aircraft and perhaps at a more cost effective rate! (something even the most hardest private jet passengers are considering these days!)