I can either get 2 500GB SSD's for around $210 or get 1 1TB SSD for around $240. What is the pro/cons of each? Any help would get great!
2x 500gb: little bit cheaper.
1x 1tb: little bit faster, less cables to manage, but costs a bit more.
Or you could get a 1tb MX500 for $200, which is comparable in terms of speed and quality.
I was looking at the mx500. Looks like a really good deal.
2x500GB: 2 (mostly independent) points of failure, but you only lose up to 500GB in the event of one drive failing. (Unless you put them in RAID 0 or a similar configuration.)
1x1TB: 1 point of failure, but you lose all of it if it does fail.
Always backup your essential data, regardless.
2x500GB: Accessing 2 drives independently can offer better performance under certain circumstances. (For example, if you need a scratch disk.)
1x1TB: If you end up moving it to another system down the road, such as a laptop (or certain SFF builds), a single drive would be more convenient. (Though you couldn't split it to share the benefits of snappy storage between two separate systems.) Also note that most laptops don't have 2x 2.5" drive bays.)