I recommend ASN.1 PER over any of the myriad byte-aligned no-schema formats that waste bits on ranges of values and entire types you aren't sending. But this is better than some other formats I've seen.
is that wrong? if not, i think many people would prefer something more open (more implementations; less likely to die from lack of support)
[edit: sorry, i am talking rubbish here. they are all linked from here, for example: http://en.wikipedia.org/wiki/Abstract_Syntax_Notation_One
i have no idea why i thought they were closed. has the ITU policy changed recently?]
Still don't think this old telecom technology is superior compared to modern serialization tools like Protocol Buffers.
PER is the only format I've seen that uses the schema to decide how much information the recipient actually needs to decode the message and just sends that, rather than adding pure overhead just in case a recipient has no idea what's going on yet is somehow supposed to do something useful with the message.
I think such approach is more flexible than making explicit assumptions on how much data is actually carried in integers.