There were a lot of responses to my last post about this topic so I think it'd be better to post this as a poll. I tried to get the main points that people made into this poll.
So for the first question you should pick the one feature that is so important to you that if it changed you'd switch formats.
For the second and third questions choose the features that are important to you (in order of preference) that you would use to if one or more formats supported your prior important feature

If you choose "other" for one of your choices please post what that other feature is!

Moderation: Amended "Error Correction" to "Error Tollerence" (and then correctly to "Tolerance" (thanks foosion :-) ))

None of the popular lossless codecs (if any of them) have error correction.

Tagging Robustness> what does that mean?
Compression Priority Adjustment> doesn't it mainly depend on the encoding GUI?

For tagging robustness I mean that it can contain plenty of tagging data to make the user happy.

For compression priority, that was what someone mentioned on the prior thread so it is something improtant.
I'd agree that is a gui feature, but it is also a make-or-break feature for some people. Hence they'd switch formats over it.

I believe that someone was me . For many users such as myself who are not fond of command line options, the GUI experience is often as important as the performance of the codec itself. There's no hard and fast rule about CLI vs. GUI, just that different people prefer one of the two for different reasons. I'm a hardcore GUI person, which means that I prefer not just a GUI, but an effective and intuitive GUI. Thus, I support the inclusion of "Compression Priority Adjustment" even if it is dependent on the GUI and not on the encoder itself. Thanks, mike'.

OS support is number one for me (I use FLAC). I have Linux and OS X at home, and Windows at work. For me it offers the best support for playback, encoding and decoding. Vorbis comments and replay gain round out the package nicely.