Having the right credit card can help you save money and give you access to airport lounges. I have tried quite few cards and one can safely rule out Amex and Diners club cards from the list. This is because these cards are not widely accepted in India as well as abroad which really ties you down and you them actively to earn enough points.
Almost of all of these cards have tie up with either an airlines or travel websites, so if you are a frequent flier or prefer a particular website then it may influence your decision.
Amex Platinum Travel Card : This was my first travel credit card and one of the reason i went for it was first year fee was being waved off for it and lesser fee was being taken for years thereafter :). This card is quite rewarding with lots of vouchers being offered [Indigo vouchers were being offered earlier but now i believe its Spicejet] and lots of rewards for heavy spending including flight + Taj Vouchers. You also get discounts on Makemytrip. This also gives you access to travel lounge with may be 4 complimentary visits. So overall a very good card but only if you spend heavily. I discontinued this as Amex is not accepted widely.
Citibank Premier Miles Card : This was my mainstay card till recently. It comes in both Visa/Mastercard and you can choose which one you want. The biggest benefit of this card is the point system, you can redeem your reward points to make payment on yatra.com [this can change] or on the premier miles website. 100 reward points are equivalent to 45 rupees which makes it quite rewarding. Along with this you also get access to domestic airport lounges. You can also transfer rewards points to Airmiles of different airlines. Additional points are given on card renewal and also as a welcome benefit. You get additional points for using card on specific sites. A perfect travel card with no issues of acceptance anywhere with only one drawback that you dont get access to international airport lounges. But i recently discontinued it as Citibank was not transparent enough in its charges and always tried to extract money. Also when you use this card, you are then completely dependent on one website, for me it was yatra.com.
HDFC Regalia Card : The only reason i have this card is because i got it for free and it gives free access to international airport lounges, 6 per year, not a bad deal!! HDFC generally gives it for free for lifetime. Don’t go for it if not for free.
Co branded airline card : After trying out multiple cards, i realised it better to go for an airline card as its lot more rewarding in terms of saving flight costs. You earn frequent flier airmiles at must faster pace which you can then use to book air tickets. There are loads of such cards on the offer, so first select which airline you prefer. I went for Jet airways as it has good connectivity and also it has partnership with multiple airlines which can also be booked with those airmiles. I took Jet airways card from ICICI bank as it gives you a complimentary Amex card along with Visa or Mastercard which accelerated points scheme. So you can use either Amex or Visa/Master for same account, a very nice concept.
There are many more cards in the market and i generally evaluate my cards every six months to see if its giving me real benefit. Depending on usage and requirement one may select different cards but having the right card for your usage helps you save money.