I've Just ordered a Vertex 4 myself... But only because I got a big discount due to damaged packaging - 256GB for £145
I've just completed reading More reviews than I care to and the choice basically comes down to in this order for a performance drive:
Samsung 840
Pro (a pretty easy No. 1 choice performance wise)
OCZ Vector (FarCry 3 free with it currently)
OCZ Vertex 4
For the more budget minded:
Samsung 830 (if you can find it, and cheap enough - prices too high due to rarity now. Is a decent choice)
Samsung 840 (an interesting drive. Perhaps "maybe" the Best budget drive for people putting less data through their systems - check out Anand's Light Workload benchmark tests)
Kingston HyperX 3K - pretty good but usually overpriced Sandforce drive
Corsair Neutron GTX
Mushkin Chronos Duluxe (A Good Sandforce drive + cheap & using Toggle NAND. Also Mushkin's tech support is 1st rate.)
Crucial's drives are good, but lagging a little behind these days.
I gave 2 of the most informative review for the Samsung 840 (non Pro) as this is a really interesting cheap option, but uses unproven TLC NAND, which Could degrade unfavorably over time performance wise. If it does not degrade like HardOCP suspect, it will be a Very Good choice of drive for the money.
I was about to buy this drive (kinda short on cash this min) till I got that Great price on the Vertex 4
Basically all the historical problems with any of the above drives are now resolved. Just be sure you have the most recent firmware installed before setting up your OS etc... (obviously you know + already have SATA mode set to AHCI in your BIOS)
Note: some older motherboards use inferior SATA III controllers like the X58 chipsets with the Marvel SE9128 will not deliver the performance a top SSD can provide.
The SE9182 though is excellent.
- basically saying, the performance at the end of the day is not down to only the SSD
Any of my top 3 performance drives will offer a significant improvement over your Agility 3 drive.
Anything from the Kingston HyperX and better would be a nice choice with improvement.