ok you have to realize the word "stronger" is a very general term. stronger in what way? every material has its strengths and weaknesses. its a matter of finding the best material for the job. pla at room temp is a very hard and strong plastic however its has such a low thermal resistance that parts will get soft just holding them in your hand from your body heat. for me that makes pla completely useless and the weakest of all filaments. i only use it for a quick prototype that will end up being tested and tossed in the trash or something that will just sit on a shelf in my house. abs is softer which in some ways may make it seem weaker but its more impact resistant because of that. the glass point is also a good 40-50c higher so its a much better plastic for something that is a functional part. abs does layer bond really well IF you get a good quality abs and you print it at the right temps. all in all though there is no perfect, strongest filament that will fit the bill for everything. definately look into petg though. esun makes some good stuff.