Building a Tyranid List: Fast Attack

OK so we are about to tackle the fast attack option for the Tyranids. Lets start with the shrikes. I love the idea for these guys, but I do not know if I would vouch for these seeing as how they have very little defense. Basically you get a Tryanid warrior with wings and a worse save (5+). Their redeeming feature is they are jump infantry synapse. So if you ran them behind gargoyles they can provide synapse as well as get a coversave. I do not like them because bolters take them down rather easily. They are too fragile for their cost and use. However, I love the forgeworld models and have contemplated a flying list using them. You can deepstrike them, fly them around, and do some fun stuff with these guy, but I just think their function is better preformed by others. These guys cost the exact same as the normal warriors and have many of the same upgrades so feel free to try them out if you want fast synapse and cool minis.
Next we have raveners. These resemble warriors with snake tails, but are a little different. They are lower leadership, not synapse, feed, and the best part is beasts. These guys are some of my favorite models but I have never been able to justify bringing them for what I do. I do know a guy who uses several of these, however, and he finds them quite effective. They can be absolute terrors in H2H so try to get these guys there (shocking :P trying to get a nid into H2H). I think they have their uses depending on your strategy. they are great to deepstrike into or behind cover due to being beasts. this guarantees a coversave and a likely charge next turn. Now these guys get a very cool character who was absent in the last codex: The Red Terror. On his own he is almost as much as three raveners, so he is not price efficient. I however would love to use him because of his swallow whole rule. If he hits with enough attacks, he can swallow a single model. This is NOT instant death so eternal warrior is no defense. Now he cant do it to very bulky or extremely bulky, but still. I love the image of his swallowing that annoying character with 3+ wounds and ridiculous saves. Not a competitive choice, but the Terror is a lot of fun. Overall, raveners have their place in specific army tactics and strategies... just not mine
Skyslashers...... flying rippers.... why... just.... why.... I mean cool idea, but these are just as bad as their normal counterparts. Still, apply them like I suggested in the troop evaluation and they can be useful...ish.
Gargoyles! one of my favorite units in the codex due to how they look flying toward your opponent en mass. I was initially upset at the change of blinding venom which is what made them so good last codex. Now they have changed. Instead of bogging down an opponent with tons of attacks to kill them, you want to blind them. This changes them from a killy unit to a support unit. They are useful still as mobile cover and now flying them in from to take the initial over watch fire then apply blind softens the opposing unit up for other stuff. Now these guys are only initiative 4 so they will be attacking at the same time as many models meaning they do not get to apply their debuff first round before the enemy attacks. These aren't quite as good as last edition, but still useful with goo synergies.
Harpy. The model I wish was a better sculpt. I personally hate the model as it looks like a bloated flying fleshbag. Oh well. I like the anti infantry uses of the harpy. It bring a lot as a flying anti infantry MC. Bring it just for that. It is not a necessary bring but a cool idea. Bring it and use it to bomb light infantry and MAYBE assault if the target is a weaker target (tau, guard, etc). It will basically rape anything not meant to kill elite classed units. 
Next is the Hive Crone. This flying bug has one big shiny strategic value... our ONLY dedicated anti-flyer ability. Its vector strike is strong against flyers and its arsenal isn't half bad. More useful than the harpy due to our abundance of anti-infantry already. I have yet to try either of these flyers so I cannot vouch for either by experience.
Spore mines. Got extra points you just aren't sure where to put and you cant just add more gaunts? Use these! they arent amazing as a bought unit but still kinda cool. The Biovore unit drops these anyway so I never bring these guys but if you want a cheap deepstrike kamikaze unit that can potentially hit at strength 10, go ahead and bring em. They are great distraction because you have to shoot at them to kill em without blowing up. Now this make the free biovore ones better, but don't be shy about these ones if you really wanna try them out. just don't rely on them due to having "instantly killed" in their hidden profile. Fun, but not competitive.
That concludes our fast attack! Now obviously unless you build a list geared to use them, this is our most available slot group on the FoC. The choices give very interesting options for different strategies. Do not be afraid of trying different units against different opponents. Some are better than others. I hope you enjoyed this section and feel free to add anything in the comments!