Options: Spined Thopter, Razor Swine, Immolating Souleater, Grim Affliction, Phyrexian Swarmlord
There are quite a lot of aggressive cards in this pack. Razor Swine can be hard to deal with and will have a big impact if not dealt with straight away, Immolating Souleater can potentially win a game out of nowhere if your opponent isn't paying attention. Spined Thopter will put a lot of early pressure on as you can play it on turn two (it is somewhat comparable to the 1/1 flyer with infect from Scars of Mirrodin). Grim Affliction is decent removal, and proliferate is a very powerful mechanic, so something to consider highly. The Phyrexian Swarmlord is very powerful, and can run over your opponents in a few turns, but you need a certain number of supporting infect creatures to make the most of it. I guess you could play it as your only infect creature (hey, infect can still be powerful in low quantities), then if you can get one hit you will see the benefit very soon, but if its upkeep trigger can happen the first upkeep it is in play, all the better. It can either create a load of chum blockers that hurt your opponents creatures slowly to keep you in the game, or produce an overwhelming force to take your opponent down.
Pick 1: Phyrexian Swarmlord, the double green is a drawback, but the card is very powerful
Pick 2: Grim Affliction, it's decent removal, no reason not to pick it really
Options: Slag Fiend, Whispering Specter, Blighted Agent, Gremlin Mine, Shrine of Loyal Legions
The Slag Fiend looks interesting, but I'm not sure if it is great in limited or not. The Whispering Specter could be powerful but seems like it would be hard to play correctly. If the Blighted Agent comes out early, it can win a game slowly on its own, even better if you have something to boost its power. Gremlin Mine is cheap, can go in any deck, and is going to be useful against almost every limited deck in this block. Shrine of Loyal Legions is another card that can just win games on its own, especially if you are either playing white or can make the game go on for a long time.
Pick 1: Shrine of Loyal Legions, the board advantage it is possible to get from this should not be ignored
Pick 2: This is between Gremlin Mine and Blighted Agent. I think I would take the Gremlin mine because it can go in any deck (the agent can too, it can win on its own as your only infect creature, but requires you to play blue).
Options: Slash Panther, Grim Affliction, Porcelain Legionnaire, Blind Zealot, Shattered Angel
There was also a Surgical Extraction in the pack, but there are too few cases where it would be worth playing it in limited. Someone I draft with on Thursdays rates Shattered Angel very highly, I have played against it once and it kept me from winning a race (I was attacking aggressively and needed an extra land to hit with lethal damage with an untamed might, but couldn't play the extra land because they would be two life up at the end of it). I quite like Blind Zealot, it can sometimes get rid of problem creatures, although intimidate isn't going to be as good in an artifact heavy block. The Porcelain Legionnaire can be hard to deal with, and will affect combat if you don't have a removal spell for it; I played against some 3/1's the other day without first strike and they were annoying enough as it was. I have mentioned Grim Affliction before; a very powerful removal spell. Slash Panther looks good, it is aggressive, although sometimes you're just going to cast it to get an attack in once, or it will just be blocked by something a bit bigger for a similar cost.
Pick 1: Porcelain Legionnaire, I'm taking this over the Angel because it doesn't commit me to being in white, the first strike will be relevant more often, the life gain from the angel won't always be worth anything, and it comes out faster.
Pick 2: This would probably be between the Angel and Grim Affliction, and I suspect I would go with Grim Affliction, because it is removal and proliferate is powerful. It can also be played as a splash, whereas it would be a lot harder to splash the Angel.
Options: Glistener Elf, Forced Worship, Mutagenic Growth, Gremlin Mine, Porcelain Legionnaire, Mycosynth Fiend, Brutalizer Exarch
There is a lot of strong green in this pack, which means the likelihood of the people on your left going into green is high, so it is somewhat risky, but that shouldn't put you off picking a strong green card too much. The Glistener Elf is risky because it will be aggressive early on, but outclassed pretty quickly, so you will need to get a lot more infect creatures to make it worthwhile. Forced Worship is reusable which is a major bonus, but they can still block (although I had a creature that had the equipment that meant it couldn't block enchanted with it so it could do nothing). It is good in a controlling deck, or one with lots of evasion. Mutagenic Growth is a very good trick to have as it is so hard to play around. I have talked about Porcelain Legionnaire and Gremlin Mine before. I have played with Brutalizer Exarch before, it is very useful and has a surprising range of options. I have not played with Mycosynth Fiend before, but have heard it is very powerful, and I will hopefully get to play with it in the future.
Pick 1: Porcelain Legionnaire again, can go in any deck, is hard to deal with and aggressive.
Pick 2: This is between Brutalizer Exarch and Mycosynth Fiend. I would probably go with the Exarch as its utility will always be helpful, whereas the Fiend needs me to take some infect creatures to make it better than a grey ogre.
Hopefully the next time I look at some first picks I will have played some more games so know the cards a bit better :D