with this much budget u have successfully eliminated 125cc category bikes from the options,,, now u r left with 2 options first is 70cc (honda cd 70) or so called 70cc chonda bikes which incluedes all those bikes labelled 78cc and in reality they r 85cc,,
secomnd option is 100cc like honda cd 100 orjunoon,yama 4 and the suzuki 110cc or so called 100cc chondas which again are lbelled 100 c but r 110 cc,,
reliabilty imainly depends on how much care u take with proper maintainance a chonda will work as better as branded ( yamaha,suzuki,honda) ,, similarly without proper care ny of branded is the worst,,
vibrationless, that again depends on care and mainly on design,, and most importantly the speed at which u will be ridin,, riding at peak speed will certainly cause some vibrations,, s if u buy say a chonda u will get a comfortable ride at upto 60-70km/hr after that speed vibrations will start to appea,, or controle will start to loose,, long and short ask urself how fast would u be riding,, and remembber these 70cc bikes can go fast but becomes extremely difficult to control them,,
all bikes has sound,, some call it sound and like it,, the sound of 125 is what makes it a hot cake to some,,and similarly the high pich sharp sound of 70 makes it distinctr from others ,, so much o ppl judge the condition of bike from the exhaust,, and while all of these are called sound by some others will call them noise, disturbance,, list to the sound of few bikes that u like and tell if u like it or not,, decision will be easy then,,
engne of 70cc bikes are very mature,, and reliable ,, they have perfected all of its parameters,, just buy some good reputation company bike like dyl,hero,pak hero,unique,super power,metro,ravi,,etc these r pretty muc reliable engine,,
another issue u must consider is road grip,, all bikes have good road grips but they are good only in some range,, after that u cant trust it,, for speeds upto 60 all 70cc will be very good,, for speeds above go for 100cc or 110cc,,
another thing is body reliability how reliable u want its body to be, most r either the classic desin bikes which has too much metel body (mudguards other nitty gritty parts,,) or plastic body ,, which tend to break crack easily so u cant repair them would have to replace them,, and its usual for a bike to filp over once in a blue oon,, so decide urself,,
looking at ur range and personal prefrence i would go for unique 100 (110cc) or sprinter or junoon,,
,marzi ao ki ani ha,,