for sector i like ops team =/.. decent damage and slow combo, so u can almost do 6-8 attacks befor ur enemy got knocked, imo in sector speed doesnt matters that much, u just lure hard to kill enemy and bring ops(tele it)... but its not good for base cuz its pretty easy to push and really slow.
The mercs i personally think works good in both base and sector are DH, Sharps, Grounder, Arsy(just if u know how to use it in base)