I think Gargraves with Ross switches looks the best and are well proven.
T-rail is VERY cool but crazy expensive and curve radius is limited.
I use tubular O27 height track, wide radius curves (O42, O54 and O72), mostly for nostalgic reasons. Easily cut to fit too.
I don't care for the look of the plastic roadbed on FasTrack and RealTrax, also, too many pieces for many needed curves. Is anyone even making RealTrax anymore? Potential inventory issues in the future