A Str-Base Builds favors the beginning Rogue. Dex-Base Builds take more knowledge about how to fight and play the class. Acrane Buffs currently favor the Str-Base Build because of the amount of Str stacking buffs vs one Dex buff.
The best way to go is to build two or three Str-Base Builds and two or three Dex-Base Builds to 6th level. Play with the Ability Scores until you find your sweet spot on the build that best matches your playing style.
Now if you are going to go Str-Base and TWF you need to have at less a 17 base Dex to take the full TWF line. More experience players will reach that level be using a +1 or +2 tome.
Now if you are going to go Dex-Base, you need to keep in mind that your Str needs to be in the mid 20's or higher at 20th level.
Con, Int and Chr are all important too. Starting Rogues need to have at less a 14 starting Con to give them the needed hit points to live on. An Int of 12 or 14 well give you all the Skill Points you need and a high enough DC for Assassination. Chr is what makes a Rogue the do all character of the game. With a UMD of 37, you will be able to hit all the important scrolls and have 90%(18 or lower) chance of hitting the 40 UMD scrolls.
As a new Rogue, you well need to max out DD, OL, Search, Spot, and UMD. Now with UMD, it does not come into play until you are a high level Rogue. You well start to noticed this when you can start using any weapon or item as you level up.
Now Str, Dex, Con, Int, and Chr all need, in my eyes, to have +2 tomes on them. Others well agrue this point but it is just the way I feel. As for weapons, Backstabbing Damage is the great equalizer when it comes to damage. Use what you like or can afford.
When it comes to STR vs DEX or Rapier vs Khopesh, well stand on a very tall ladder. Just remember the most important rule of being a Rogue. Rogue is spelled R-O-G-U-E not r-o-u-g-e.