let me clear some details here ... brothers...
GS150 is a class apart, it got ~11 BHP it got good road Cleareance it got every thing a user wants including a self start in a 1lac package.
having said that, lets keep the BYQ paiggio aside as its not in market so its useless to compare, lets compare it with Storm 125:
1 - they lamest thing one would say is its from CHINA (get a life you Nokia is from China too so thats the stupid most way of measuremnt of quality)
2 - It is also 11BHP bike
3 - It offers Disc Braking
4 - it Offers better tyres for quality Road Grip (Imagine the skinny tyre which comes with GS)
5 - it can Cruise on long tours at high speeds
6 - it has dippers and light switches
7 - It has intelligent self (wont self start if in gear and clutch not engaged )
8 - Self adjusting auto Valves and tappets
9 - Clear winner in fuel Economy (well known to have good mileage)
10 - gear indicator, fuel gauge, you name it its there....
11 - Add off course its a direct and clear winner in modernized looks and shape.
all the point which I mentioned above are not present in GS and most of the time people buy a GS and then add these qualities to it and it costs a lot and needs a lot of time specially to make it a disc braking bike, where as paiggio offers it in only 1lac package.
All in All both bikes are Good but Storm Gives you more in a same price.
SOME POWER SHOW DOWN from GS and RP :
Thread which may help you:
https://www.pakwheels.com/forums/bikes-3-wheelers/207634-piaggio-storm-evolution