you can ask the same question over and over again, and the majority of people are going to tell you to go Asus. they've been one of the forerunner for quality for years, so much so, that it's ingrained in most GPU & motherboard afficionado's mind that if you want the best build & service quality, Asus is the only answer 3000 rupees (i assume from the name)/ $50 be damned.
both are reference cards at reference clock so performance isn't going to differ all that much, and neither is cooling seeing both look about the same. and even if that last part isn't true, Asus has shown to be great at cooling.
either way, that leaves you with comparing the two cards based on assurance of build & service quality. now most people here don't familiarize zotac with quality all that much, so you know what most, if not all people are going to say regarding the subject. but seeing as how the two zotac gpu owners i know of never complained about the brand, you could try risking it. and i do emphasize the word "risk" as two satisfied customers don't make much of a solid guarantee.
when you're gunning for a 690, i reckon you'll either go for broke or forget about getting it in the first place. what's wrong going another $50 for a $1000+ card, eh? if price is a major concern then consider a single 670. assuming you are using rupees as the currency, i just saved you 30K+. may not perform the same as a 690, but it does it's job well enough for a single 1080p monitor setup.
but if you're using 3x 1080p monitors or a single 1600p monitor, add in another 670. based on these pricings;
http://www.flipkart.com/computers/computer-components/pr?layout=grid&sid=6bo%2Cg0i&otracker=start&q=gtx+670
2x Gigabyte 670s = 53,000 rp. you get close to the performance, if not equal to a single 690, for 14000rp less than the Zotac, and 17000rp less than the Asus, if flipkart's price are anything to go by. plus, it's from Gigabyte, so there's some assured quality there.
http://www.flipkart.com/zotac-nvidia-geforce-gtx-690-zt-60701-10p-4-gb-ddr5-graphics-card/p/itmdbc7vyyzmuhpq?pid=GRCDBC7SHHR8KUVD&ref=88998b04-f0b7-410a-889c-ae81e811e8e6&srno=t_2&otracker=from-search&query=gtx%20690
http://www.flipkart.com/asus-nvidia-gtx-690-4-gb-gddr5-graphics-card/p/itmd9uqvhvggz5nb?pid=GRCD9UP5AA6SNEYZ&ref=88998b04-f0b7-410a-889c-ae81e811e8e6&srno=t_1&otracker=from-search&query=gtx%20690
and in case you're still doubtful; a single GTX690 is simply 2x GTX680's, downclocked. a GTX 670 performs VERY close to a 680, with a 5% loss at worst. 2x GTX670 in SLI, at stock clocks perform about the same as a single 690. overclock those 670's and you just got the best graphics card setup for the right price.