I'm using blocktrades too.
For me it's fast, simple, convenient. I believe you can get a bit better rates on markets like polo but after factoring in fees and time spent wasted on trading you won't get any better than on blocktrades. Worth to mention that those guys are involved in the platform so I think they do care about STEEM price.
You might think that polo is cool until you have to solve even the smallest issue with their support. ;)