All of them.
mars
The planet that moves through the background of stars most slowly is Mercury. This is because Mercury is the closest planet to the Sun and has a shorter orbit period than the other planets, resulting in a slower apparent motion against the background of stars as seen from Earth.
The planet that has the slowest orbit would be Neptune due to the fact that is is furthest away from the sun. However, if you want to count dwarf planets, then Eris would be the slowest.
When that happens, the planet moves from east to west, from our point of view. This should not be confused with the daily motion of all stars + planets due to Earth's rotation; rather, to the planet's movement against the background of the stars.
A planet's predominant movement (NOT the daily movement related to Earth's rotation, but the apparent movement compared to the background stars) is from west to east. If a planet moves in this direction it is said to be "prograde", if it moves in the opposite direction, it is said to be "retrograde".
Actually, the apparent westward drift of the planet compared to the background stars is known as retrograde motion. It occurs when Earth, which moves faster in its orbit, overtakes and passes the slower-moving outer planets, making them appear to reverse their usual eastward movement in the sky.
You observe its motion, with respect to the background stars.
Relative to the Earth, almost all stars are moving faster than any planet is.
"Parallax shift". We can't SEE the difference in position of any star as seen from the Earth 6 months later or earlier, but by measuring the very tiny differences in the positions of the more distant stars, we can observe the "parallax" of a star and thus calculate its distance. This only works for stars less than about 300 light years from Earth.
Stars in the night sky appear fixed, since they are much further away than planets. The planets can be identified through their apparent brightness and their movement among the background stars over time.
The sun's apparent path through the background of stars is called the ecliptic. It is the apparent annual path that the sun follows as seen from Earth.
The planet that comes from the Greek term meaning "wandering star" is "planetes," which translates to "wanderer." In ancient times, planets were seen as "wandering" stars because of their movement across the night sky in relation to the background of fixed stars.