You ask whether to square the block or the quilt. The best answer is neither. Be sure that each unit is exactly the right size as you assemble it (careful cutting, sewing, pressing), and then nothing has to be trimmed at the end. Of course that is advice that we all forget to follow from time to time. Starching the fabric before it is cut helps to keep it from stretching. There are methods for Hunter's Star that wind up with no bias at all (using HST's) and other methods where you do deal with some bias, but it shouldn't be all bias.
It would help to see your blocks, or at least know what the problems are with them. Are they roughly the same size? If you cut them to the same size, will you lose the points when you sew them together? Are they roughly square? If they are wonky (a good quilting term), it will be difficult to make them go together without trimming, but it will also be difficult to trim them without losing points. Sometimes the best course is to take some of the blocks apart and fix the problems in the components that make up the block. Sometimes the best course is to make more blocks. I have a few really wonky ones that I keep around, just to remind myself to pay more attention earlier in the process.