I don't recommend getting JUST a SSD. The prices of high capacity ones of a good quality are just to much. The best way to get performance and storage for a good price is to get a good SSD like the Samsung 840 Evo at 128 or 256gig and then a HDD for storage. I currently use the 256 Samsung 830 and a 1TB seagate for backup and storage (as well as a 3.0 USB external for music/movies so I can just plug it into my TV when I want).
As far as Single, multi, and triple level cell (SLC, MCL, TLC) goes, as a consumer there's not a lot to worry about. SLC will have the best performance and tend to be the longest lasting, but at a higher cost. They're not really made for the consumer and you don't see a lot of them on the market. MLC was the basic consumer standard until TLC came out. Both give up some speed and and longevity in lifespan for a better cost. Now when talking about lifespan I'm talking heavy usage drives can start to see a decline in performance after 7-8 years... possibly. This isn't really something to worry about for the average user.
It's best to shop for SSDs by looking at performance/cost ratio and quality, balancing everything to get what you want.