What’s the source of your footage? Is it HD? DV25? DV50? SD uncompressed? Your source will make a difference on what you render to.
Otherwise:
DNxHD – for HD sources.
1:1x – Uncompressed 10-bit
DV – DV footage
DV100 – DVCProHD footage
Meridien Compressed – SD footage. This is a legacy codec and can transfer back to older Avids, but works great with new ones too. This is at least a 2:1 compression, good only for SD footage. Your AE comp must be set to 720×486 (NTSC, not sure about PAL) for it to render. Anything else and it craps out.
Meridien Uncompressed – same at Meridien Compressed, but it’s 1:1 – uncompressed.
Does this help? Also, do you need to render with an alpha channel? If so, that changes things.
Michael.