A TwoTiered Approach to Assessing the Habitability of Exoplanets  Abstract
[1507.06293v1] Earth Similarity Index with two free parameters
Earth Similarity Index  how much some planet or moon resembles the Earth.
This is an attempt to quantify how similar a celestial body is to the Earth, as a way of identifying possibly habitable ones, at least ones where living things can inhabit the surface. It uses:
 Radius
 Mean density
 Escape velocity
 Surface temperature
Averaging the first two values gives an interior similarity index, and the second two gives a surface similarity index. The overall index is the average of these two indices.
The PHL page has a formula for this ESI, and it also has a simplified one, one that uses only a planet's radius and its star's light flux at it.

The most Earthlike SolarSystem object is Mars, with interior = 0.82, surface = 0.60, total = 0.70. That is using actual surface temperatures. Using a naive estimate of proportional to 1/sqrt(distance) gives srf = 0.60, tot = 0.71.
Venus is int = 0.98 and srf = 0.20 (actual), 0.78 (naive), tot = 0.44 (a), 0.87 (n). That planet's atmospheric greenhouse effect is what makes the difference. That is another complication in assessing Earth similarity, because a little more received light may give a planet a Venuslike runaway greenhouse effect.
Mercury and the Moon have int = 0.84 and 0.67, and srf = 0.42 and 0.46 (actual), 0.39 and 0.69 (naive), tot = 0.60 and 0.56 (a), 0.57 and 0.68 (n)
The next one is Io, with int = 0.35 and srf = 0.19 (actual), 0.18 (naive), tot = 0.36(a), 0.35 (n). The remaining SolarSystem large bodies are worse, often much worse.
Turning to exoplanets, the Wikipedia article's list of high scorers are all planets of red dwarfs, with the exception of Kepler62e. That planet's star is a K5 star, between the Sun and reddwarfhood.