1.5jz is better cuz the 1j head has better flow. that's it. with the 1j i suggest going with a programmable ecu. i've had nothing but problems with the stock ecu. when it runs... it runs great... when the ecu decides to fuck up it sucks. i enjoy my 1j great engine, runs smooth even with solid mounts it's really just up to what you want to do with the car and how much bang for your buck. 1j parts are really expensive but it's a unique engine in my opinion and a lot less mainstream. and i say do the swap yourself - with some help from friends and people on here you can get it done for a lot cheaper.