There are threads in which people argue at length about Monokote and Oracover (called Ultracote in the U.S.) Some people prefer one, others like the other one. Don't take any one person's word as gospel. As for tissue, if you are building a small, light model and the instructions call for tissue, either Monokote or Ultracote would likely be too heavy and too likely to damage the framework when shrinking. You wouldn't use tissue on a .40 size sport model, but you wouldn't use an ordinary film covering on a 1/2A Texaco model, either, at least not on the wings. Coverite makes a lightweight covering called "Coverlight" which is easier to apply than tissue and lighter than conventional films. Both tissue and silk take some skill to apply. What model are you building?