These threads are always minimally useful.
Those two bikes are going to ride very differently. I was never fond of the Sunday, nor its DW Link designed suspension. I've always stuck by and liked single pivot designs, or just simple designs in general. The reasons to get a Sunday in this thread so far are pretty redundant: 1. Its more reputable? Why? Cause Sam Hill rides ones? Or are they reputable because the Linkage sucks and it comes loose on its own. 2. Looks. Function before fashion.
I'm not a huge fan of the Sunday. I really encourage the original poster of this thread to test ride a Sunday. Some people absolutely love them, some people don't. I'm not saying its a bad bike, its a good bike and they've made improvements to it, but you really need to make sure that you like the DW Link design and the geo the Sunday offers. Its a very fast bike.
The EC-D is a pretty solid rig too for the price. Both bikes are spec'ed pretty well for their price tags. It's all going to come down to which frame suspension design you like best and which geo you see fit.