This type of cement comes in two flavors, a paste in a tube or a liquid in a jar. It only works on hard plastic (polystyrene). It actually dissolves the plastic and fuses the parts together. Use carefully or you will ruin surface detail. I do not use tube plastic glue and liquid cement sparingly. I prefer superglue.
Without hyperbole, superglue has revolutionized modeling. It dries instantly and rock hard.
Superglue comes in different viscosities (super liquid, liquid or gel/paste). It also comes in different drying times. Unlike plastic glue, you don't have much time to reposition because this stuff dries immediately!
Superglue works on anything, hard and soft plastic, metal , and resin. I use superglue gel as a general purpose glue and liquid superglue as a seam filler, or to give a hard surface to puttied areas (especially when using wax). Another reason to use superglue is that it is removable! Superglue uncure is a liquid that will dissolve superglue. For example, it is great when you have smeared some glue onto surface detail. Pour some uncure on it, wait a couple minutes and see the superglue soften up enough to be wiped away. Uncure and superglue do not attack polystyrene so after clean up it is the same as if nothing happened. The downside of superglue is that it has no flexibility whatsoever. Beware when cementing small parts, such as antennas, or guns. The join is as brittle as glass and will snap under any pressure.
Superglue in three words: instant gratification and reversible.
This is a superglue based paste, available in hardware stores, that dries flexible, with a rubbery texture. It is tricky to use because it dries instantaneously so you have to use fresh glue all the time with a wastage of 95%.
I use goop if I need a flexible bond. For example, for pikes and spears, I cut off the head of the plastic weapon and replace the shaft with pianowire. The plastic tip is glued to the metal shaft using goop. Fresh goop sticks immediately and stays flexible enough when dry to tolerate some misuse. I started out with superglue but the tip would fall off anytime it was touched.
Goop joins can be removed easily by just pulling the parts apart. Use uncure to remove any residue.
Epoxy glues come in two parts that need to be mixed prior to use. It dries hard with a very strong bond. It dries very slowly. Some epoxies have faster drying time (5 min) but that is eternity compared to superglue.
I use epoxy infrequently, only in situations which require a lot of repositioning and a slower drying time. It also requires that the join can hold by itself. Try clamping down without moving for 5 minutes.
This is standard household white glue. It is milky white and dries transparent. It is available anywhere you can get school supplies and is sold at a premium in hobby stores. The only use I have for it is to glue clear parts such as canopies. It dries clear so does not cloud the part. You can remove excess glue with a toothpick when wet and cut it with a sharp knife when dry. It can also be used to fill small windows like airliner side windows. It is not ideal because it does not dry as flat surface.