Crucial c300 and Crucial m4 in my opinion are the best drives to go for. I think the Crucial c300 are the tip top best consumer ssd's on the market still to this day even though they are previous gen models. They still have the fastest random 4k read which is the most important spec for standard consumer desktop ssd's and they also hold up well on random 4k writes but they are beaten by the new vertex and the m4 on the writing side of things but they are still faster in writes over most drives and write speed is not very important for home users.
The crucial c300 also uses the older 34nm flash chip process. All the new gen ssd's use 25nm process. Yes the 25nm process allows greater densities of storage lower power usage and cheaper to manufacture but the 25nm process also lowers the durability of the flash cells so the c300 are also more durable and longer reliability than all the new 25nm based drives.
I'd say the choice between the c300 or the new m4 comes down to which size of ssd you want to get. Some sizes are close in price and some are much cheaper on the m4. If the c300 is only slightly more than the m4 then you should go with the c300. If the m4 is significantly cheaper then it's prob the best bang for the buck. The c300 is worth paying a little extra over the m4 as it has faster random reads and higher flash cell durability. But if you need that 512GB size than m4 is your only choice other than that they both come in 64GB (perfect size for strictly an OS boot drive), 128GB (perfect for OS boot drive and all applications with leftover for a few games), 256GB (perfect for a dual os [windows + osx] and all your apps and a buncha games) and finally the 512GB ***M4 series only*** (perfect for people that want all the speedy ssd storage space they can get regardless of price.)
In conclusion, go for the 128GB Crucial c300. This specific drive holds the crown as the worlds fastest 4k random reader (4k random reads is the spec that tells you how fast your boot time is gonna be and how responsive your system will be with launching apps and such it's like 95% most important spec for almost all normal home users). You'd think the 256GB would be but since it uses a larger block size it actually makes it slightly slower.
128GB should be large enough for most average peoples home ssd install.