Jeb is a vote for amnesty.
So there’s an issue you disagree with him on. That issue will never come up if we have firm Republican control of the Senate, and of all the issues facing our country, that is not the most important one (though I agree with you on that issue and not with Jeb). Jeb is reliably conservative on the VAST majority of issues he would face as a senator. His stance on immigration is somewhat understandable given his Mexican wife and his broad support among Cuban and other Latino voters in Florida.