Ted Cruz definitely has his flaws, and his inability to play nice with the others in Congress is one of those. There is no avoiding the fact that Cruz is not the most likeable person. Unfortunately the choice for GOP nominee appears to be the choice of the lesser of two evils. On that score, Cruz is definitely the lesser of the two available evils. Trump has extremely high negatives, especially among people who will vote in the general election. Trump also has outrageously stupid policy ideas, most of which simply cannot be implemented. Trump also has a very distinct record of supporting liberal causes and policies in his past, including his recent past. Trump is also displaying mistakes bordering on incompetence when it comes to running a successful campaign; that definitely does not bode well for his ability to run the executive branch. Finally, Trump is even further out of the graces of the rank and file republicans in Congress than is Cruz, meaning that doubts about Cruz' ability to get things done are dwarfed by doubts about Trump's ability to get anything done.
Cruz has flaws. Trump has more and greater flaws. Since the choice is for the better, not the best, Cruz is the better choice.