Hi mate, welcome to the hobby!
I hope it is a long and fruitful stay!
Hopefully my advice is helpful to you; I've been in the hobby on and off for about 10 years, and I have lots of experience with Chaos and Space Pups.
First, I'll breakdown your initial impressions;
"
-CHAOS-
Pros
Aesthetics - I love the painting opportunities.
Oh yes, Chaos Marines are a huge codex that caters for so many different legions and themes it can get quite confusing at times. Few codices will offer you the modelling variety of Chaos.
Havocs - Cheap and lovely (but the conversions, oi. See cons below.)
There aren't many armies that can have firepower as effective as Havocs, that is for sure.
New dex- New and exciting! Heh.
Yes! Yay!
Cons
Troops- Other than throwaway units like Plague Zombies and Cultists, I'm not liking the troops. I do enjoy Plague Marines and such, but I don't know if I can stay interested in an army that is too heavily 'Marked.
Troops tends to be an area Chaos Marines aren't as good in as the other 'top' codices, i.e. Space Wolves, Imperial Guard and Necrons. However, the real kicker for Chaos is the significant amount of customization - we have lots of variety and lots of good ways to outfit our troops. The best way to work out what works is to try the different options out and settle on one that works with the rest of your force.
Conversions- Seems like it will take a lot of conversion to make work (havoc autocannons, etc).
Yes, that is a problem I am having as well. Our kits tend not to have all of the options represented, and as such conversion will be necessary to get what you want most of the time. Forge World is a good place to go, but for autocannons, you will have to improvise; I've looked at Aegis Defence Lines and Dreadnought Autocannon arms, with the thought of cutting them in half, but size and price are a deterrent. Your LGS owners might have some good suggestions.
Complexity - CSM armies strike me as needing Allies and I don't want to do that right away."
I don't think so personally, we can put out some very good armies by ourselves. Our major problem is that we have too many good but not fantastic choices in our slots - as nothing really stands out, no real 'netlist' has emerged as yet, and thus a lot of people would quickly dismiss the codex. It doesn't encourage spam army lists, it encourages balanced forces.
-SPACE WOLVES-
Pros
Fluff- Love it. I enjoy the elite feel of a band of heroes with their own sagas.
I've yet to meet someone that dislikes the background of the Space Wolves. They are pure fictional awesome.
Thunderwolf Cavalry- OMG want.
You will love them and they will love you. Talking from experience though, they can be a pain in the butt to assemble and transport (a friend of mine has a lot of them).
Troops- As I understand it, Grey Hunters are some of the best troops in the game. As a new player, I might need to rely on a strong base. This will help.
They are arguably the best Troops in the entire game, period. There aren't many codices where you can take almost entire armies filled with a specific Troops choice and be competitive. Grey Hunters are so much better than other Space Marine equivalents it isn't funny.
SPACE VIKINGS- I mean, c'mon.
Yes!
Cons
Cheese?- Another player at my local store called the Wolves cheesy when I was asking about these armies. I know it shouldn't bother me, but is this the case?
They aren't cheesy, trust me. It just so happens that they are one of the top codices going around as far as tournament play, especially in 5th Edition. They have two of the most points-efficient units in the entire game in their respective slots - Grey Hunters and Long Fangs. They have some nasty options and their psykers have access to ridiculous powers. Like any codex, they are only cheesy if you make them that way - there are very few units in the codex that are bad, and as such you won't be punished for taking lists that are different to what WAAC gamers would tell you to take. Thunderwolf-heavy armies can be fun and deadly on smaller boards, and Space Wolves do Drop Pod armies better than many others. Just don't spam Grey Hunters in four or five squads in addition to spamming Long Fang squads and your opponent won't get angry at you.
Redundancy- I may play Dark Angels when they come out in <insert rumored date here>. I worry about having too many marine armies.
This is an issue I've had and come to terms with lately. The first 'marine' (i.e. non xenos, non-chaos) army I collected was Grey Knights. As much as I also want to do Salamanders, another marine army just isn't as appealing to me. It is quite funny considering Grey Knights are the most unique of the Marine codices, but eh. If you pick Space Wolves, I'd recommend a Xenos army afterwards. But if you really want to do Dark Angels when they arrive, I would recommend Chaos.
Points- I love Terminators and Thunderwolf Cav. They will suck up my points like crazy, right?
Oh yes, although it also depends on how you outfit them. Whilst Thunder-Hammer/Storm-Shield (or TH/SS) Terminators are amazing, Space Wolves pay a lot more points to use them than other Marine armies. As such, the codex encourages you to use Terminators in other ways. Thunderwolves are pretty cost-effective base considering how amazingly quick and punishing they are, but upgrading them can really ruin your budget. I would recommend Storm Shields on Thunderwolves, and the close combat upgrades are situational - Rending will do you well most of the time, but a thunder hammer or equivalent weapon in a unit is a good option."
My personal advice to any new hobbyist is to go with what looks best to you; when I first returned to the hobby a year ago, Chaos looked the best to me, even though at the time they had a very weak codex. My subsequent armies followed a similar trend; I loved the look of the Dark Eldar, and the aesthetics of the Grey Knights. However, my evaluation of the rules available to each army has also played a part in my decisions; this is why I avoided picking up Tyranids, Eldar and Chaos Daemons. The approach of a new codex also should affect your decision; Space Wolves and Chaos won't be re-done for a long time, so no worries there. But if you ever consider armies such as Chaos Daemons, Tau, Eldar, Orks, Tyranids, Space Marines and the like, be aware that they are all likely to be re-done within two or three years.
If you can't decide after that, there are two funny solutions I've seen people use; one is to find one unit, particularly a character, in either codex that you think is just so awesome that you simply must have them and then go from there, or toss a coin (or roll a D6 if that is more appropriate).
My last point might be a bit blunt; if you want to have the more competitive of the two armies, take Space Wolves. They are simpler to use than Chaos Marines and you aren't as spoiled for choice and thus won't have too many issues picking out what you want. Whilst I don't think Chaos Marines are a bad codex, they aren't in the top tier with a handful of codices; they are meant for balanced play, not to be OP (although obviously codices aren't written intentionally to be OP). But if you want an army where you can adopt a visual theme that appeals to you and can be really tailored to suit your needs, go for Chaos.