american express travellers checks

Credit cards are definitely the more popular route these days
Depends where you are and what sort of budget you're on. If you're staying in $5 hostels and eating from food stalls where a typical meal costs the equivalent of $1, you need CASH. Therefore you need a cheap way of accessing your cash from ATMs, which isn't a credit card.

Agree with joolz...I rarely (almost never in fact) use my credit card while travelling.It is there as an emergency backup if and when needed.

Debit cards on the other hand......that is the best and cheapest way to get your money (via ATMs).

Yes, it is important to differentiate between credit cards and debit cards. Credit cards are for paying for things, debit cards are for getting cash from an ATM.

"Also, you generally get the best rates with cash and okay rates with debit/credit cards"

That is incorrect jpyrek. The best rates are not for cash but for debit/credit cards. Even cards that charge some foreign exchange loading are cheaper than exchanging cash.

That is definitively not true. I confronted this all over Asia and Africa and the rates provided on all of our credit cards/debit cards were always worse than the cash rates. Many times the cash rates would be better than mid-market.

I recall when the cards were ALWAYS the best, but that was confined primarily to Europe. I have yet to find a developing nation where a card rate is better . I understand that this has to do with the financial institution through which you hold your card, but even in groups of folks from the US, UK, and Netherlands, all with different banks we found this to be the case.