A tanking fighter?Human?
If human there's a great 16th level pure build and the 18th level enhancements that are I think on the way are reason not to splash too much IMO.
But if the difference between the 12th level and 18th level enhancements of those lines (Defender, Kensai etc) isn't too great then you will have 8 levels to play with come 20th level when they are introduced.
I think I specced a nice 10/4/2 (Ftr/Pal/Rog) build out on the old PC with the 2 rogue levels being taken at 8 and 16. The rog levels give you enough skill points for max UMD,balance etc and the evasion ability which you may find handy in those non-combat moments when you need to dodge stuff like a lot of fireballs, traps. Paladin gives you immunity to fear, immune disease, lay on hands, Charisma Bonus to all saves (which is nice) etc. I'd take the feat (Force of Personality*)that adds your charisma to will saves as well so you get it double on Will saves which is typically weakest on Ftr builds.
*I'd take that on the pure build as well and just don't start you Cha below 10, but don't put anything into Wis.