For $150 you are not going to get a crankset as stiff or strong as the XT.
Because shimano holds a patent on the hollowtech cranks, others are forced to use a "C" shape, or an "I-beam" type. You aren't going to get comparable stiffness or strength out of these as compared to the hollowtech due to surface area.
I suggest the LX cranks, a great value for the amount of stiffness and strength provided, you also get great shifting rings.
Whatever you do, stay away from ISIS, due to the large axle, ISIS BBs are forced to use small bearings, which wear out and destroy themselves very fast. ISIS never worked anywhere near as well as the shimano octalink BBs. The shimano external-BB cranks are better than the older octalink stuff, but since other manufacturers are moving to external BBs this is less of an issue, except that you'll find ISIS stuff on sale really cheap.....for a reason.
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