That liquid stuff in a can is more or less for sealing and patching over a real roof. It sucks for sure and the time it says it lasts is bull. I didnt do but a couple rubber roofs. Its called EPDM. A synthetic rubber comes in wide rolls. Not sure on max width but at least 12'. Only needed if on low pitch areas. If your not in a windy zone (you wont need to adhere to deck) and its not too large where you can get a wide roll to cover the area with no seams edge to edge and 4 - 6 inches over the fascia then stretch it and use an aluminum strip with holes and screw it into the fascia & cut off excess. If it needs a seem there is a sealer/glue. Thats a good roof. Probably good 40 years or more. Theres another type called Modified Bitumen. Comes in 3' wide rolls. 2 kinds. Torch applied (hot) and chemical applied (cold type). The seems are welded together either with a propane torch or with a reactive chemical. Those are the 2 best roofs for roof areas under 4/12 pitch. Thats a 4 inch drop in height for every 12 " level length. You can check it with a tape measure and a straight board or however. These rubber and bitumen are the best for low pitch because lower the pitch the harder to keep the water running off and not pooling or building up and coming through. Those types above were once exclusively commercial application but are now used in residential. Theres a science to all of it but your uncle or roofer friend will know what to use If its not a low pitch say 5/12 or above you can go with shingles. Dimensional or architectural shingles are better of course more money than standard 3 tab shingles. It depends on your area as to how much you should spend on materials. Here we have sun, rain and wind to deal with and the codes are high and reflect the zone and whats required. A 3 tab standard shingle roof only lasts about 18-20 years here because the sun is brutal. May last a lot longer where you are Codes for your area are a good reference but you can go under depending on how strict they are about inspections etc. Just dont go way below what they reccomend in quality and installation procedures. Personally I would put the best you can afford and no cutting corners within reason. Here you cant hardly do a roof without a license. Its difficult for a homeowner to get a roofing permit without one. They throw people in jail nowdays if you do shit without a permit no shit You dont want to do it again in 10 or 15 years and get leaks in between etc. The other option that is good is corrugated 3' wide steel sheet roofing panels. They will roll it through a machine and cut to your custom lenths. Easy to install if you dont have a lot of cuts like valleys and oddball shit all over to deal with. Long lasting. Good durability. Maybe lifetime. It works pretty good at a 4/12 pitch maybe even a little lower. Its good looking also Research online to get an idea of what you like best and really whatever is most common type roof in your area is usually the best choice with some exceptions. Depends on whats available in your area too.