Ok welcome to the forum man... So here is the best scoop I can give with my knowledge from 99 to 2014... The 00- 06 are a tried and true workhorse. Personally I love them more for the longevity vs the nnbs.. Simplicity is also nice too... Cheap to own and maintain also.
For features and comfort the 07-14 is hands down awesome. From the seats, to the suspension and steering, the traction control etc. Hence why I have owned a few for sure also. So known issues I can tell you about...
AFM failures are real, mostly due to people not doing maintenance etc. Most of our vehicles are already past the first owners, so seeing what they did is key. CARFAX report will show you intervals of oil changes etc to help that out in your decision factor.
The 6 speed trans is a large step in the enjoyment of driving. The 4 speed going up to 2008 was ok, tried and true but had some issues all its own.. The 6 speed is a better trans than the new 8 and 10s that are out, Id keep the 4 or this 6 any day compared to the failure rates of the new ones so there is a check in the positive for the 07-14 pltf.
Dash cracks are normal on all 07-14, deal with it is best I can give you on this. Dash covers are cheap and look pretty good. 00-06 dash paint flakes off thats the normal on those.
There are little quirks here and there on everything. End of the day. This is the 3rd NNBS I have owned. Tahoe LTZ- 2009, Suburban LT 2012, and 2011 Denali XL... I am very **** about my vehicles and how they drive. This is the one vehicle I keep going back to.
PPV/ssv stuff rides rougher just be warned, they can be picked up alot cheaper, but NO 3rd row seating etc either.
In your position, put a few more k together. I sold my 2012 suburban Leather texas edition, 140,000 miles for 10500 cash 4 months ago... You can find them in that area also just may have to negotiate down.
I think the Variable valve timing on the 2010 and up really make the motor use up some of the held back performance.
Stay away from vehicles from Salted road places.
Stay away from hybrid ones due to repairs being not the cheapest.
If I was to pick you something to hit the 7-10k mark.. 2009-2011 tahoe, suburban, yukon... 140k to 150k miles. There is still life in it for sure, just check carfax data on service history and accidents etc. That is key... Reason I paid more than market on my yukon I own now is the service history is very detailed on the report.
For 7k and under 03-06 with anything less than 200k you will be good... Just put some money to the side for repairs if needed. There are tons of them still on the road and they are the most durable suv for a good price point.