Hi Samvinay,
I don't know your budget, and generally speaking, people tend to match entry-level AVR's with entry-level speakers. If your like "Laid-back" sound with good bass then I would recommend Wharfedale 9.2 pair (@ 14k approx) as fronts for your Onkuo TX-SR304. (Many on this forum have recommended Onkyo+Wharfedale combination... Onkyo is little forward sounding, whereas the Whafedales are laidback)
I would request others on this forum to suggest matching surround and center speakers. (I have Onkyo HT-R518 receiver with 9.2's as fronts. The surrounds and center speakers are Onkyo that came with the receiver as Home theatre set)
Regards,