There are numerous threads in the Performance forum (and others) about the Quad4/Twin Cam engines and a rampant debate thread is currently running that I'm not getting involved in. But, if your goal is simply "more power", either one will do. If you have other needs, have a donor car with either engine, have significant funds available to mod as you see fit and as far as your imagination runs, you're good to go. Realize though, that engine changes in these cars aren't exactly plug-and-play. You'll need the transmissions and electronics for either and there are some that would contend that the change to an Eco would be little more trouble and more desirable. Do a little research and you'll see what I mean. - Good luck.
