I have installed, setup, and test flown a number of entry level flight stabilisers. The one I prefer if buying on price alone is the NX3 from Banggood.
It has 3 operating modes, (2 stabilised). It has a basic stabilised mode, an OFF mode, and a mode akin to "SAFE" mode.
In the SAFE mode the model cannot be flown inverted and will self right if the control sticks are released.
My personal favourite stabiliser is the ZOHD but it is more expensive and has a GPS - return to home feature.
Have fun!