Padauk is the one and only almost-truly-Unicode-compliant. The only problem with Padauk is they use Graphite rendering engine. You need to install a special build of Graphite-enabled Firefox. Graphite rendering is slow for a very long Burmese page. And if you type in Padauk using Microsoft Word, it won't render correctly. You will also need a special Graphite-enabled word-processors such as OpenOffice.
Myanmar1 from Myanmar Unicode and Natural Language Processing Research Center is also said to be standard compliant. It's not completely done yet, I think. Correct me if I am wrong.
MyMyanmar, according to their web site, can also support true Unicode encoding.
ZawGyi-One and MyaZedi do not follow Unicode standard.
I personally think that the best and most elegant solution is Padauk.
My issue here is not to suggest you what font to use. Just to suggest to think in the long run. If you think your data are important and want it to be future-proof, please do research about the commitments of the developers of the fonts you are going to use. Make sure that it can be easily converted to future true Unicode encoding. The problem with partial encoding is that the future of your data will be at the mercy of the developers of those partial Unicode fonts. If they don't provide you any tools to convert to the new and latest standard, you will have to write your own converters if you are a programmer. If you are not, you are at the mercy of computer programmers.
If you absolutely have to use one of the partially-compliant Unicode fonts, please research their web sites for their committment to the future. Otherwise, it's better just to stick with old ASCII WinMyanmar fonts for now.
My experiences with Myanmar fonts
I have been involved in Burmese-English dictionary project for a while now. The dictionary was typed in Chitwin font, one of the earlier Myanmar fonts. We just had to write our own converter from Chitwin encoding to WinInnwa because Chitwin is too old. No converters for that encoding can be available from anywhere.
From WinInnwa to Unicode is easy because we used Keith Stribley's TECkit converters.
Now that our dictionary data is in Unicode standard encoding, any standard Unicode fonts can display our web site correctly. Padauk can do it using Graphite-enabled firefox. MyMyanmar can do it with regular firefox.
If the Unicode encoding is modified in the future, I assume someone will have to write a converter from old unicode to the new version.
In my personal opinion, it is the safest to go with the standard becaues we are not relying on any fonts, Padauk, MyMyanmar or Myanamr1 per se. Upgrading from the old to new version might be complicated. But somebody definitely has to write the conversion tool. It's inevitable.
Paper and standard specifications on Myanmar Unicode
Representing Myanmar In Unicode, Details and Examples by Martin Hosken and Maung Tun Tun Lwin
Myanmar Unicode Standard