They are both a bit different, but overall I'd say testopro is likely a better choice. It both raises total testosterone, as well as lowering SHBG giving you more free testosterone so maximizing your natural testosterone levels. Mass FX is primarily based around some of the plant based steroidal type compounds, and some people get hit or miss results from that. I used t-bol (older formulation) from thermolife as high as double dosed and got minimal results. Mass FX does work well for some people, just not everyone.