The 510 is a solid drive and one of the very few SSDs to have never received a firmware update for bug fixes. It is expensive however. Too expensive IMO.
The m4 has shown to be a solid drive. It has had issues but these have been swiftly dealt with by Crucial.
The Corsair is a Sandforce drive and thats a whole subject on its own. For me, the platform has had too many problems to recommend to other people.
I would also look at the Samsung 830.
This ^
I recognize many people claim because you use a Samsung 830 somehow your opinion is flawed. Untrue. I use Intel and back this guy up 100%.
Samsung 830 is the way to go. Only other option I'd consider is the Intel 520 which hasn't been officially released yet, but you'll pay big bucks for that.
You can get close-enough QA to Intel going with the 830, toggle NAND, cheaper prices, a SSD toolbox included, insane speeds and all in-house Samsung parts (not going to hurt your reliability, that's for sure).
I couldn't in good faith recommend anything but the Samsung 830 to anyone who hasn't won the lottery, in which case I'd say get the 510.
Nothing wrong with the Crucial M4 or the exceptional support those drives have received, but they are like my SSDs, older and bested by newer models at this point. 830 > M4. I wouldn't buy a G2 today just as I wouldn't buy an M4.
On brands I'm a bit of a sticker on SSD toolboxes, which only Intel and Samsung offer. You get the option to run manual TRIM commands, check on the life of the drive and run other diagnostics. While all drives are in the same ballpark for pricing, not having a slick utility like this (which also updates your firmware) is inexcusable in my mind.
Personally I'm willing to wait for the Intel 520 480GB drive. I'm also willing to pay for what will probably be the end-all ultimate SATA6gb drive we'll ever see until we move to a faster connectivity method.