clean, straight chain-line, with sufficient ground clearance
Brommie - out of the box
Tikit - has to be upgraded to an IGH; that adds about 330 (Nexus 8) to about 700 (Alfine 11) to the base price.
In fact, for the Tikit to have the same gear range as the 6-speed Brommie, the Alfine 11 would have to be used (though Brommie's gears are higher)
Why not use the stock derailleur or get a double chainring up front and have an even greater range? The Brommie six-speed hybrid gearing setup was designed that way because of the fold...but it's not an optimal touring set up, and there's not really a point in trying to imitate it on a touring bike. Most people who tour do so with a traditional derailleur set up.
You don't need a suspension.
Get the nylon travel bag for the tikit and pad it with foam; the bag costs $70.
There are other advantages to the Tikit - for one, you can buy their folding rear rack and carry normal panniers on the rear of the tikit - this allows you to carry much more weight on the tikit; for another, the tikit comes with "V" brakes, which are better than the standard brompton brakes. (Also, the T-Bag is kind of pricy at $160).
But what to get really depends on what your primary use case will be. If you want a touring bike that you can also commute on, you should probably get the tikit (with single or double derailleur). (Assuming you've ruled out a 20" folder like the NWT). If you primarily want a commuting bike and the smallest possible fold is important, you should go for the brompton.