SignCut is by far one of the easiest to use.
Vinyl Master is very powerful for the price. There are 4 different levels of Vinyl Master so you can pay only for the function you need.
Flexi is usually thought of as the 'best'. Many professional sign shops use Flexi. Flexi also has various versions so you can pay for what you need. Likely, you would go with Flexi Starter. Compared to Flexi Starter, Vinyl Master would give you more bang for your buck.
WinPC Sign would be another to consider as well. Not sure about support for that cutter though. I would need to check.