First of all, there is not a "Best Pure STR Euro Build at Lv100".
Secondly, you have a pure STR FF at 90 and is going to start another one? Well, I guess it's not my business so whatever.
I'll try to help anyways, but I'll just give the cons and pros of these builds, as there is not one that is "best":
Best tanking build amongst these, very good and useful at group pvp. Very good at 1vs1 pvping. Slow at solo pve. No speed.
You already have one FF at 90. If you don't know the cons and pros of this build then kill yourself.
High speed, has stealth skill, very high damage dealer, very versatile (combines speed and range from crossbow with meele damage from daggers), best at solo pve among these. Not so useful in group pvping though it has party speed buff, and can change to bard and use mana cycle, dances and so on.
No speed, has stealth skill, better at solo pve than any warrior build (except maybe warrior/bard), useful and good at group pvping (cleric skills), good at 1vs1 pvping, better tanking than rogue/bard.
All of them are good damage dealers, all of them are good builds, it depends on what you prefer.