So I am in a bit of a dilemma and would love fellow travellerss help!

Trip

I am planning on leaving around January 21st 2016 and I find that the airfare to Mexico City, MX is the same as to Cartagena, CO! I intend on spending about 2-3 months in either region, moving frequently between places.

Desires I have never been to either of these regions and mostly desire to backpack and explore where I go to. I enjoy the history/culture/food/etc. Id love to be in some rain-forests and see tropical life too. Mostly just want to background the world. I dont have a big agenda just to explore places Ive never been!

Shelter

I plan on taking a tent with me and sleeping were I easily can. I also plan on using CouchSurfing and maybe even airbnb or hostels as well.

Transport

I intend to mostly use cheap buses or maybe hitchhike depending on where I am and where I am going.

Budget

In case its not already obvious; as cheap as possible! Realistically Id like not to spend more than $1000, (Is this possible?).

Myself

Also I will be going alone (23 y/o white male from USA). ~63 and 185 lbs.

I composed a very basic positive and negative of each (Im sure much is missing, or even wrong, so feel free to add to it or comment on it):

Positive for Mexico –

Yucatan peninsula and all that entails (Mayan ruins, Cancun, etc.)
Can get back to the USA fairly easily by bus then fly/hitch back home.
There is the Veracruz Carnaval.
Perhaps not so much a culture shock? (smaller leap that all the way to S.A.)
I am easily able to explore Central America.
It seems that there is somewhat better international coverage for my phone around here as well (which is very important to me as it is my anchor/guidance/lifeline)
Also Southern Mexico seems like its a bit safer than Colombia/S.A. (I would fly right over the Northern)

Positive for Colombia –

Shorter, non-stop flight for much further at the same price
Barranquilla carnaval
I would get to explore other parts of S.A. (Probably western coastal areas)
Could attempt to see the Amazon
Perhaps it is more adventurous as I am going further away? Negatives for Mexico –

Not going as far for the same money (about 3000, miles shorter I believe)
Im not sure if that really matters much but its the only one I could really think of.

Negatives for Colombia –

Would pretty much have to fly back and depending on where I am and the date of travel it could be very expensive.
It seems a good deal more dangerous (not certain, was just looking at the government travel advisories there are.)
It feels more nerve-racking just thinking about it to be honest.

So there you have it! Thanks so much for reading and any input is valued very much. I am very flexible and if you even have an idea for an entirely different area I am very receptive – you might change the course of the rest of my life!

Thanks again, you all are awesome!