What echoes you want depends on what you want to do. Are you more interested in rigging? More interested in hacking? Also, does your game use dice pool caps?
A fairly general answer in priority order:
Very Good: Sprite Link for any of the following you don't have: Tutor, Machine, Code, Sleuth one of [Paladin,Fault]. Macro. If you care a lot about rigging, Overlocking, Advanced Overclocking.
Good: If you care a lot about hacking, and don't run into dice pool caps, Widget. If your GM thinks Swap works in the good way, Swap 1-2 (the good way being it reduces the penalty for doing anything while having a CF threaded, not just for threading a new CF while having a CF threaded, and that it reduces the penalty per CF, not once).
Could Be Worse: Multiprocessing, Swap if your GM thinks it works in the OK way (where it reduces the penalty only once, not per CF, but otherwise as above).