I've taught English in Ecuador, Brazil, Thailand, and Australia, but in my opinion the best place is Spain.
Here are some of the reasons why I've been living in Seville, south Spain, teaching English for the last 6 years.
Spain might be in a crisis, but the TEFL industry is booming. Spanish people NEED to learn English to help them in the job market, parents are prepared to pay extra for their kids to have a good level of English because they need a high level to get into the best universities. What does that mean for you? That there are lots of jobs.
The weather is gorgeous; blue skies for over 300 days a year.
The food is amazing. Seville is rammed with tapas bars and quality places to go out and eat. You can have three tapas and a couple of beers or glasses of wine for under €10.
The students are great. I teach 7 to 18 year olds during the afternoon and adults in the mornings. Fair enough, you do have the odd grumpy kid and dull adult, but in general the students are keen to learn English.
The life style is comfortable. For about 24 teaching contact hours you can earn between €1000 and €1200 and live well. Rent can be anything from €200 for a shared flat to €600 for your own pad. You can eat out one or twice a week, travel a couple of weekends a month and still save money. I do extra business classes to boost my wages.
The people are friendly. I've just got married to a Spanish lady, who used to be my student I might add, so I am biased. You do get a few odd balls, but in general they'll treat you well.
There's an interesting culture. Flamenco, bullfighting, a long history, and many museums and churches will keep you busy in your free time (which you do get a lot off while living in Spain). There's a relaxed way of life and I wouldn't change it for anything.
So what are you waiting for? Get TEFLing in Spain.