I have used Samsungs & Intels in most of my new builds - my desktop has a 120GB Intel 520 and I tested the Samsung 830 in that same build before putting it in my laptop. Both drives are incredibly fast and would be great system drives. I personally like Intel a little bit better but I buy whichever one is a better deal at the time of the build which has been Samsung for quite some time now. I picked up 3 of the 128GBs for $90 each off newegg the other day so if you're patient, you can get a steal of a deal.
If you're putting it in a system that needs more than 128GB for programs, systems files and games then I would probably go with either the 180GB Intel or the 256GB Samsung depending on which one is less expensive at the time. Regardless what you go for, bring a spare change of underwear. Seriously...it's that awesome
I would consider both to be equally good. However, in quick succession, I recently bought 2 Intel 520 SSD of 180GB and 120GB. They are great so far and read speeds in AIDA is 525 MB/s. Connected to SATA III. Samsung 830 was not available at the time in India (out of stock with my vendor).
Have 3 Curcial M4's (two 128 gig M4s and one 256 gig) also three Samsung 830's (2 128gigs and 1 256 gig)
Both the M4 and the 830 256 gig models have recently been on sale at New egg for $180.
In real life performance, not a nickels worth of difference between Intel 520, M4s and 830s. I prefer the controller in the m4 and the 830 over the SF controller in the Intel 520. Reliability / Least user problems - Very simular for all three.
For Desktop, recommend the 830, IF PRICE NOT too much over the M4. For Notebook go for the M4 as power consumption is lower. (This mimics Anandtech recommendations last time I checked.
Bottom Line, if you can hold off and MONITOR newegg sales get the 256 Gig 830 or the M4 as I'm SURE they will be onsale for $180 Again!!
The performance in normal usage of all SSD's is remarkably similar.
At equal capacity, Intel 520 and samsung 830 are very similar in performance.
One big determinant of performance is how much of the drive you fill. As the drive gets filled to near capacity(80%) updates take longer; perhaps significantly longer.
Therefore, to answer your question, the 180gb drive would be much better. It is absolutely much better if you intend to put as much as 90gb on the drive, in which case, the 120gb drive(110gb useable) will not be so good.
Today, I would stick with Intel or Samsung for reliability. They make their own nand chips, and can do a better job of validation.