I've used them both quite a bit and it really comes down to personal preference. As to which is more powerful, you could beat your guns & hands silly figuring that one out (and I have). I finally decided that the 45 Colt worked better for me.
I use it in an old Vaquero and my heaviest load is a 335 grain Keith style gascheck wadcutter at 1190 fps, give or take 20 depending on which chamber fired it. It shoots these close enough to the sights, which are regulated for 255's, to make it useful for swatting big critters out to 50 yards or so. I could never get a 44 to agree on two loads, that far apart, without cranking on sights.
It may be a quirk of this particular gun, but it works for me and I like it.