Personaly I'd go for a twin if you have any motorway mileage in mind.
The transalp is a great little bike, but lacks a little power especally if you intend to carry luggage.
For the purpose you have in mind, IMHO, the AT or GS are your best bet.
I love Africa Twins. There very robust and have enough power for solo or two up riding with luggage and have a decent tank range. They are mechanicaly fairly simple, being carbed but, it can be a bugger to get at various components. Having said that, the fuel pump in generally the only thing that can course problems. They are very reliable machines.
GS's are robust, comfortable, have bags of power and torque and have a reasonable tank range. You can load them up with luggage and you won't notice it's there. The shaft drive is a distinct advantage as you don't have to carry chain lube and oil the chain every day.
The best thing to do would be to get as many test rides as you can before you part with your cash and go with the bike that you enjoy the most.
Keep us posted as to which bike you choose.