Leaving the budget aside, and assuming you haven't checked it out yet (or at least not in depth), have you seen the Sony Xperia Z2? I've owned a Galaxy S3 for a year and a half now and have had both S4 and S5 in my hands... Both barely evolved (other than some minimal fancy shit) regarding the previous one. Not worth it imo. This year when I get the money I'll no doubt go for the Z2, not touching Samsung again for a while.
NOW that's a merely personal opinion, if this is your first high-end phone (just like the S3 was for me) then either'd be okay. Can't comment on the M8 though, never had it. They barely sell any HTCs here at all.
NOW that's a merely personal opinion, if this is your first high-end phone (just like the S3 was for me) then either'd be okay. Can't comment on the M8 though, never had it. They barely sell any HTCs here at all.