Not sure which carrier you're with, but often times you can get even better deals online from the carrier's website (and sometimes wavied upgrade/activation fees also). I debated quite a lot between the HTC One and the S4, and picked the S4, but my wife got an S3 and loves it. If I could have it my way, I'd take the guts of the S3 or 4 and put it in the body of the HTC One.
I personally don't like the skins that HTC OR Samsung put on their phones, so I always install Nova Launcher and make it look like stock Android, so I threw out all the extra "features" that come with SenseUI (HTC) or TouchWiz (Samsung). If you plan on keeping their skins, then you can consider those features. I'd personally lean towards the HTC One, but that's just a personal preference. I do love my S4!