Not too sure what you mean rendering at 1k or 2k, just use the resolution for the system your using. (PAL 720 x 578 (I think off the top of my head))

Ive never had problems with loss of quality (using maya->After effects->Avid Express pro) so it could be your settings from one to the other.

I usualy render out at std 4:3 but have been playing with widescreen. end of the day its up to you and the what you need it for.