You are in luck. I currently own both. S&W Sigma 40VE since 2006 and Taurus 24/7 for 3 months. I'll try to list all I can about them:
Weight - The Sigma is a lighter gun. That is good for carry but not great at the range. It definitely has more kick when shooting.
Capacity - The 24/7 carries 15 + 1, one more than the Sigma
Safety - The 24/7 has an external safety in a traditional position. The Sigma has no external safeties.
Trigger - I've had a trigger job done on my Sigma bringing it down to about 6.5 lbs of double action only pull, from 10. That said, the 24/7 is a single action trigger and the pull is noticeable lighter. Both have a pretty crisp break. My Sigma has a bit shorter reset and the Taurus has a bit longer initial travel.
Reliability - Both have been very reliable and not finicky about ammo choices. The Taurus has a double action second strike capability if the initial primer strike fails (I like this feature as I shoot a lot of reloads and encounter an FTF in about 1 of 100 bullets almost always due to primer)
Grip - To me this is a big difference with the Taurus winning hands down. The "Ribber Grip" of the 24/7 is the best mfgs. poly grip I've handled. It is very stable and cushions the hand well. A must for long range sessions with a 40 cal. Most people add an overwrap to the Sigma for a better grip.
Accuracy - I find them to be pretty equal. I shoot the Sigma better but just because I've had it a lot longer.
Durability - About 5,000 rounds through the Sigma and 500 through the 24/7. No complaints about the durability of the Sigma. Likewise from what I've read about the 24/7.
Cost - Got my Sigma for $250 after a $50 rebate and two extra free mags. That's $250 for the gun and 4 mags!!! I bought the Taurus for $359 and it came with 2 mags. Mags for both cost $35 - $40.
Rails - the Sigma rail is labeled as an accessory rail. It is a bit thick and blocky and I've heard tails of some equipment not fitting. The 24/7 rail is pure Picatinny and should accept anything.
Hope this helps.
