Making lists seems to be a great way of making a total non-relevant comparison. Considering there are more than 60 entries already posted on this site, one mite be tempted to ask, which was the best? And I mite not be able to answer... But I'll try.
During the past week I have actually been trying to remember other places in Southeast Asia where I have enjoyed waterfalls and/or swimming holes. Most though are so far back, that I have no pictures to post and no real memories of them either. They were Tasik Chini in Malyasia (visited in 1990), Khao Sok (1990) as well as a 2004 journey in Khao Yai NP (Hew Narok waterfall) Thailand. That said none though are in the top 10. Hew Narok
What I tend to like is places less visited / less frequented, with a walk (hate 'drive in' waterfalls), abundant nature and different.
As said the best swimming hole I have known was at Hin Huep, Lao, though essentially nothing exceptional it formed a good part of my life.In the list I'll concentrate on waterfalls:1. Tad Xay, Bolikhmxay, Lao. A huge pool, remote, surrounded by nature.
2. Blahmantung, Bali, Indonesia. An energetic walk in, high drop, great scenery.
3. Mae Sapok, Chiang Mai, Thailand. Remote but accessible, low visited, diverse fall area.
4. Huai Phai, Loei, Thailand. Another walk in which means less visitors. Great to mess around in.
5. Lu Du, Satun, Thailand. Forgot, so maybe over romanticized ...
6. Kuang Si. Beautiful.
7. Mo Paeng, Mae Hong Son, Thailand. Interesting surroundings.
8. Huai Hin Phon, Chiang Rai, Thailand. Unknown, quiet.
9. Tad Xe, Luang Prabang, Lao. Accessible, beautiful, vibe.
10. Khlong Nam, Kampaeng Phet, Thailand. Eery beauty.
The most popular waterfalls of Southeast Asia would be something different. In that top 10 would be Erawan, Sarika, Saiyok from Thailand, Kuang Si, Lao, Khone waterfalls on the Mekong, Lao/Cambodia, Gitgit, Bali, Indonesia, Sipiso-piso, Sumatra and many more. Anyone have different suggestions?