Best place to learn to Scuba?

Its Koh Tao that you need to go to. Padi open water takes 4 days and if you stay to do the advanced thats another 3 days.
Koh Phangan is nearby and lovely to chilling out and beach time. Koh Tao is only really worth going to for diving so try to fit in both islands. have fun

Koh Tao is worth to go and there are many diving resorts. Been had Padi open water diving course for 4 days and 9,800 TBT at Big Blue diving resort. My instructor is Mr.Simon Garrity,a very nice experience with him to learn. Have the certification now. Cheers~

The important thing is to find a great instructor. If you have a bad experience diving, you won't ever dive again. I agree with Rickchen on Big Blue. I was there for 4 months, I had so much fun! I learned to dive and be completely comfortable there. Simon Garrity is a great instructor and a personal friend. I did my dives with Alex Daluiso and Simon for Emergency First Response. He is very patient and had a great sense of humor. What ever you do and whereever you go stay away from BANS! I am not saying that as a Big Blue loyalist, I am saying it for your own well being. I have seen BB come to the rescue of divers in the water at Bans and I have seen divers come to Big Blue to learn to dive after a botched attempt there.

Just got back from Koh Tao, and you DO have a lot of choice. Baan is a good shop, as is Big Blue. I did Crystal Dive Resort and helped out on a lot of open water and other courses (I was doing my DMT, Dive Master Training). Each shop has pluses... I heard Baan's (a little down the road between Maehead and Sairee) has more personable instructors. At Crystal, there are a lot of different language groups represented (like Swedish, Israeli, French and Japanese/Chinese instructors), so I guess maybe you should get there, talk to the instructors at a number of shops, and find one that suits you the best. I think all the Open Water courses take like 4 days, first day theory, a day in the pool (confined water exercises) and two days diving. I know Crystal did four dives with an open water course, and depending on the people in the course, sometimes they lasted the full 45 minutes, sometimes less (depending on the air consumption of the group).
:)
Either way, your answers here are all good. I saw a lot of satisfied Big Blue and Baan divers as well as lots of Crystal Divers.
:)
ENJOY your diving!
Dave

Yes, your friend has the spelling wrong, and as others have indicated, it's Tao (not Tai).

But there are other places than Tao to pursue dive training in Thailand, most notably the Andaman Sea side (which includes Phuket, Khao Lak, Phi Phi, Lanta, etc.). Right now (through October) the weather is changeable both at Tao (the main Gulf of Thailand dive destination) and at Phuket (the main Andaman Sea dive destination) because both areas are experiencing the shift in the monsoon winds from southwest to northeast. Southwest monsoons bring rough seas to the Andaman side while northeast winds do the same to the Gulf; during the changeover month, the weather can be bad (or good) at either place. However, the diving in the Andaman is always better than that in the Gulf in terms of visibility and abundance/variety of marine life. You can learn cheaply on Tao, but it does have a worldwide reputation for being something of a certification factory. Average class sizes tend to be large, classroom presentations are sometimes huge lecture-hall events, and there are so many dive students in the water at certain sites that it's referred to by fun divers as 'diver soup'. So if you end up on Tao, shop around; find a place that guarantees a maximum of 4 divers per group, both for theory and practical sessions; find a place that offers a full four-day course instead of cramming everything into a three-day rush. Based on my own bias ;-) I would say, come to Phuket for better diving, better chances of small classes, and a whole lot more non-diving things to do than on Tao.