I do a lot of traveling and, when I can, I like to share whatever benefits my experience might offer.So it wasn’t surprising when my daughter asked for my advice, on behalf of a friend, about which credit card is the best for earning travel rewards. The question, however, wasn’t one to which I had given much thought in a while.There are a lot of rewards programs to choose from. I am not an expert on them. I mainly use two programs, offered through American Express and Chase, but these are not necessarily the best out there. Nor will they necessarily be suitable, or even available, for everyone. Though I am satisfied with the two programs I use, I did a bit of digging to see what would be around if I were to start over from scratch today.The primary card I use for travel rewards is an American Express Optima credit card. An important note about the distinction between credit cards and charge cards: A credit card does not have to be paid in full every month. I do pay the card off completely, and I strongly recommend doing so, even if it is not required. Credit card interest charges are exorbitantly expensive, and they can be especially so on rewards cards. If you end up paying large amounts of interest and fees, it can substantially undermine the benefit of your travel rewards.The nice thing about the Optima card is that it has no annual fee, yet it earns rewards. The bad thing about the Optima card is that American Express stopped offering it to new customers in 2009. Unless you are sent a targeted offer, you can no longer apply.For an American Express option with no annual fee that earns travel rewards, the Blue Sky card has garnered positive online reviews and word-of-mouth. For every 7,500 points you earn, you receive a $100 statement credit that can be used to cover travel expenses booked any way you like. The drawback of American Express is that the cards are not accepted everywhere that Visa and MasterCard are taken. On the other hand, if you already have a Visa or MasterCard-backed debit card (or one of their credit cards), you can probably get along just fine using that to cover the instances where you can’t use your American Express. If I were looking for a new travel rewards card today, Blue Sky is the one I would likely investigate.I also ran across the Barclaycard Arrival World MasterCard and the CapitalOne VentureOne Rewards card (a Visa offering) in my research. In the past, I carried a CapitalOne card with a rewards program that I used a lot. The card added a fee that I did not want to pay, and I had some other service issues with CapitalOne, so I dropped the card. But I would not rule out CapitalOne as an option, especially because the VentureOne Rewards does not have an annual fee.I have no personal experience with Barclays products, but the Barclaycard MasterCard may also be worth investigating. The card offers a relatively high reward rate and seems to come with a fair amount of flexibility. It does, however, have an $89 annual fee. Though the fee is waived in the first year, all else equal, I would stay away from cards with an annual fee.That said, I do pay a $29 annual fee for the travel rewards program on my Chase Visa card. I have had the Chase card for a long time, and it has a large credit limit. I also use it for large purchases for my business, so I tend to rack up a considerable number of points on a small number of transactions. I don’t know that a personal user, applying today, would get as good a deal or as much value for it. The Chase program is a little more cumbersome to use, since the travel has to be booked through Chase (either online or by phone), and in my experience, not every flight is available. Though I use the Chase card, it would likely not be my first recommendation to someone looking for a new travel rewards card.If you use almost exclusively one airline or hotel chain, nearly all the major carriers offer proprietary cards that come with a variety of bonuses. The Delta Skymiles American Express, for example, allows you to waive the fee for your first checked bag. The Starwood American Express gives you automatic gold status in the hotel’s rewards program if you spend $30,000 annually, and lets you convert your hotel points to airline miles on several major carriers. However, locking yourself into one major travel provider could backfire in the event of a route change or if you want to travel somewhere your card’s travel partner can’t take you. While you may earn miles a bit faster, you sacrifice flexibility in doing so.As when choosing any credit card, you will likely get a better deal and have more options if you have good credit. Do not be tempted to simply grab the card with the largest sign-up bonus. Pay attention to annual fee levels, APR, a low spending minimum before you’re eligible for rewards, restrictions on how you can book your travel and what travel you can book, and other “fine print” details. If you plan to travel internationally, it is also worth comparing the cards’ foreign currency conversion fees. The card that is right for you will ultimately depend on your personal travel habits and needs.If you do your homework and have the discipline not to dig yourself into a hole paying the high interest on a carried-forward balance, a travel rewards credit card can be a great way to defray travel costs. And making travel cheaper is a great way to make it a little more comfortable.