That's what I meant by "it depends on your definition of Earth-like". Mars and Venus are at least debatable, many of the planets being reported as "Earths" in the media aren't. (Yet. I freely acknowledge this will change, and soon. I have no doubt that we will find rocky planets of the approximate right size in the approximate right orbit in the near future. Getting a bead on their chemistry and such is going to be a lot harder for a while, though, but we'll crack that too, eventually.) I tend to favor "actually capable of supporting life" but the equation doesn't seem to actually require that.
Mars has the strike against it that it is arguably on the frozen side of the zone of life. Earth is actually already on the somewhat cold side and has spent a fairly large portion of its life as an ice planet; some have speculated that our frequent ice ages have contributed to our diversity of life by moderately predictable periodic mass extinctions, but of course this is just a theory in all the bad senses of that phrase. Venus is possibly too far on the hot side but I have an easier time envisioning life on a relatively hot planet than a relatively cold one. We have extremophiles here on Earth and who knows what they'd be able to evolve into if they weren't in such a small niche? Whereas cold really puts a stopper on life; a critter can evolve that can survive being frozen and possibly even carry on simple life functions but only at a very slow rate, and for all we talk about how fast and robust life is it does not take very much slowdown of life before you can't get an intelligent civilization evolved before the sun ceases to support life. Life is thought to be ~3.5 billion years old here, and it's hard to pin down exactly how long the sun could sustain non-intelligent life but it could be as little as ~1 billion years. Cold life has a real challenge getting to intelligence in time. (Also why I don't spend any time wondering about life in nebulas; they may be a science-fiction staple but at the rate they could live they don't have enough time to evolve into anything interesting before the heat death of the universe.)
Mars has the strike against it that it is arguably on the frozen side of the zone of life. Earth is actually already on the somewhat cold side and has spent a fairly large portion of its life as an ice planet; some have speculated that our frequent ice ages have contributed to our diversity of life by moderately predictable periodic mass extinctions, but of course this is just a theory in all the bad senses of that phrase. Venus is possibly too far on the hot side but I have an easier time envisioning life on a relatively hot planet than a relatively cold one. We have extremophiles here on Earth and who knows what they'd be able to evolve into if they weren't in such a small niche? Whereas cold really puts a stopper on life; a critter can evolve that can survive being frozen and possibly even carry on simple life functions but only at a very slow rate, and for all we talk about how fast and robust life is it does not take very much slowdown of life before you can't get an intelligent civilization evolved before the sun ceases to support life. Life is thought to be ~3.5 billion years old here, and it's hard to pin down exactly how long the sun could sustain non-intelligent life but it could be as little as ~1 billion years. Cold life has a real challenge getting to intelligence in time. (Also why I don't spend any time wondering about life in nebulas; they may be a science-fiction staple but at the rate they could live they don't have enough time to evolve into anything interesting before the heat death of the universe.)