I don't have much experience with nids, but I do like KT... So my thoughts on nids...
Units with * should have Synapse from somewhere.
ElitesHive Guard*
Lictor
Zoanthrope
Venomthrope*
Pyrovore
Malanthrope (FW)
Hive Guards - are pretty good in terms of offence, and defence.
Lictors - Difficult, with terrain it could be possible to run around and kill key targets, or eat up enemy fire if you can get a good cover save.
Zoanthropes - Ehh Without Brotherhood of Psykers they are pretty bad... With BoP you might consider it, but without it the only function they serve is as as Synapse node (which you can get from other units).
Venomthropes - If you have a plan its shrouded could be useful.
Pyrovores - Not too bad. Even without Synapse it can be an assault unit (thanks to feed).
Malanthrope - Tougher Venomthrope with Synapse, potentially good but expensive.
TroopsWarriors
Genstealers
Termagants*
Hormagaunts
Rippers
Mucoloids (sp)
Warriors - are likely to be your source of synapse, and have a few options... A reasonable choice and very important if you want to take a lot of Termagants. A Warrior with EW should provide a survivable Synapse hub.
Genestealers- You know what these guys do.
Termagants - Lots of cheap dakka, really need synapse.
Hormagaunts - Thanks to being individual units, and having feed, these guys don't need a Synapse babysitter.
Rippers - Much like Hormagaunts, don't take spinefists if you don't have Synapse.
Mucoloids (SP) - One might be okay with infiltrate or outflank... Probably too slow either way... You have the points to get some rippers?
Fast AttackShrikes
Raveners
Sky-Slashers
Gargoyles*
Spore Mines
Shrikes - the other good choice for Synapse. Not as tough as warriors, but faster.
Raveners - Again they don't need Synapse if they aren't going to do any shooting. Very similar to Shrikes. Ask yourself why you want these over shrikes.
Sky-Slashers - Like rippers... with wings.
Gargoyles - Needs Synapse; their advantage is speed but this might cause problems with keeping in Synapse... soo think carefully.
Spore Mines - Like Mucoloids (sp)... Far too slow.
So first let's talk about Synapse options (if we want to take any). It is also worth remembering that your one of your Synapse creatures will very likely end up being your leader (if you take any Synpase creatures). Although a Broodlord would take priority over them if you could fit them in the same force (say a Zoanthrope).
Zoanthropes, Malanthope (you're only going to get one in a list), Warriors, and Shrikes.
If your not being allowed to use psychic powers from units with the BoP special rule then Zoanthopes are a no go, unless you really want Synapse but haven't got it anywhere else in your list... But for the points it would be pretty steep.
Warriors Vs Shrikes seems like a good place to start. Their stats, and available equipment/upgrades, are similar, and come at a similar cost. The basic difference is that you are trading one point of armour for being jump infantry. This probably won't make a difference when you are being targeted by heavy/special weapons as many of them will have an AP of at least 4, but it certainly will make you more vulnerable to small arms fire. Ideally Kill-Team boards should be fairly terrain heavy (25% being a bare minimum) so you can negate a lot of these problems with good use of cover. The other difference is the lack of Bio-cannons, but I do not think these are great in Kill-Team where models tend to be spread out; there might be some use for the venom cannon, but I don't think it is great. As for the other ranged bio-weapons, I probably wouldn't bother swapping Devourers for Spinefists, but Deathspitters are okay if you have the points. If youplan to end up in combat, and have the points,Rending Claws and Flesh hooks are almost certainly worth taking. Lashwhip and Boneswords are nice, but very expensive in 200pts.
I think in slightly in favour of Shrikes, but it does depend on the role you want them to do, and synergy with the rest of your list. If speed isn't an issue then we can compare these two units to the Malanthrope.
Malanthrope Vs Warriors - You are definitely losing offensive output here, and wounds, but you are getting a tougher unit that is unlikely to suffer from ID in KT, and it has a 3+ save and shrouded which will help it against heavy and special weapons. It also provides shrouded to models nearby (helping them survive). It also has the chance to provide preferred enemy to anyone within 12, assuming it can kill something in combat. This is circumstantial, but reasonable as long as you can get into combat. You also have regeneration, which while also circumstantial could keep this thing in the game. It is expensive. If you take it you'll have a choice between it and a brood of three medium sized nids (Raveners, Shrikes, Warriors) with very little in terms of upgrades, or a host of smaller nids (members of the Gaunt, and Ripper families). With the bigger nids I'd take Warriors or Shrikes over Raveners. If you do take one of the faster units you might want to consider taking infiltrate on the Malanthrope to help it 'keep up' with those faster units. If you take a host of lesser nids then the function of the Malanthrope is to boost them, but I fear that you might find it difficult to get enough offensive power out of the rest of your lists; you might end up relying on specialists who would be fairly vulnerable to being killed if they failed their cover save.
I'll add to this later, talking more about what you might take in a team, and what USRs might be good on what units.