The best bike dpends on your requirements.
How and where do you ride?
How much are you carrying?
What is your size?
What is your budget?
I came up with the following requirements for my bikepacking bike.
http://www.bikepacking.net/individual_setups/new-bike/ * durability - obviously a ‘packing bike is subjected to higher loads and will be used for several days in a row, so this is paramount.
* comfort and control - a backpack makes cockpit positioning more critical and the extra weight makes impacts harder. It is also less easy to control your body and bike with a higher center of gravity.
* low rolling resistance - the goal is to cover some ground after all, and especially on sand and rocky terrain this can be hard.
* efficient pedaling - it’s hard enough work already.
* stiff frame, fork and wheels - for better control with a heavier load
* low weight - there is enough extra weight in the camping gear and food. Also bikepacking rides have a larger proportion of hike-a-bikes than normal rides.
For me this means a full suspension 29er, but for someone else it may come out differently.
I don't agree that an open main triangle is essential. It is nice but you can compromise a bit there as everywhere else. In my Stumpjumper FSR 29er I can get the Jandd frame bag in, but it's an XL, if you ride small bikes that factor becomes more important, since your rear clearance tends to diminish as well as your stem length. so you will need to put more stuff in the frame.
If you are looking at HT 29ers I think the Cannondales should be on top of the list because of the weight and stiffness of the fork (plus you can stash the awesome
Headtool in the steerer).