I am willing to consider cheaper SSDs, although not the TLC ones, more due to the reliability and lifespan concerns. Reliability and lifespan are also some of the primary reasons I have been thinking about getting the Samsung Pro. Does Sandisk have any MLC drives cheaper than the Extreme Pro? If they still made the Ultra Plus I might be considering that, but I dont think they do. How good are the OCZ/Toshiba or the Corsair drives right now?
Where do these concerns come from, exactly?
The only reliability issues I've heard of concerning TLC was with 840 EVO slowing down considerably, but that was fixed with firmware updates and it was years ago. There may well be others I haven't heard of. But it doesn't matter, there are many examples of reliability issues with MLC drives as well. Reliability has more to do with the actual controller and firmware rather than the NAND itself, and I think SSD's have been out and about for such a long time already that I don't think there's any real risk in being an "early adopter" of a newly released drive.
As for lifespan, typical home users need not be concerned at all. The expected write endurance of Samsung 850 EVO 500GB, for instance, is 150 TB. During the 10,000 power-on hours (over 400 days) of my 850 EVO, I've only written about 7 TB on it, and it's been in pretty active use with the OS, all programs and all games installed on it. I expect it to last another 20 years or more.
Here's a good illustrative graph of the endurance differences between typical TLC, typical MLC and high end MLC drives. I've put an indicator arrow to where I'm at after 10,000 hours of daily use:
Life expectancy with 500GB capacity is much better still, and the 840 EVO in the graph does not use 3D NAND, unlike 850 EVO and MX300.
Does Sandisk have any MLC drives cheaper than the Extreme Pro?
Ultra II is MLC, and SSD Plus is MLC or TLC depending on model. Both are pretty good buys.
How good are the OCZ/Toshiba or the Corsair drives right now?
Probably decent quality, OK performance but not necessarily the best value for money. I don't know anything specific about them, I suggest reading Anandtech's or TechReport's reviews for specific info.