By far the best TBS 6" figure is the Scout Trooper w/ Speeder Bike.
Of all my TF/StarWars/Macross/Lego/Toy collection, its one of my favourite pieces.
I also highly recommend the Bespin Luke figure, which I think is the best one of the 6 Black Series Lukes.
Sand Trooper is also pretty rad. Comes with three weapons, which is just fantastic. Bit back heavy and hard to pose but.
And the classic Stormtrooper (TBS #9) is a pretty bloody awesome figure. Arguably one of the better of the whole line.
Commander Cody is a good one, and while the regular clones look good, they have some limited shoulder articulation.
I would probably give the Vader a miss - its not great. That helmet is just wrong. It seems to go for higher prices, and considering he's the centerpiece character, there are much better 6" Vader figures out there (like Mafex or SHFigs).
So long as you dont mind second hand figures, quite a few good ones pop up from time to time on ebay.
Some of the older ones (R2, Anakin, Boba, Maul) go for some pretty ridiculous prices too.
But like Facepunches said, beware the KOs (tho I have considered the $20 Darth Maul...)
TargetAU on ebay has Kylo and FO Stormtroopers for $35.
TF Figs of 2024:
1) Legacy Magmatron
2) Legacy Gears
3) SS102 RotB Optimus