Moderate Republican like Christie, or conservative like Cruz?
I voted "yes, best way to attract independents" but not because of the candidates you list. At this point I am unsure there is a moderate Republican in the current field of hopefuls, as my concern is Trump has done something to the entire GOP field exactly inverse to what Sanders did to Clinton in the race for the Democrat nod.
I have argued before that Hillary expected to walk into the White House with little to no challenge relying on the media and establishment Democrats to shield her from criticism and real challenge. Literally win on name, history, and being a woman. Then Sanders happened, and as a true liberal forced Hillary to brand herself in the same regard.
Well over on the GOP side something similar happened. Trump convinced the entire field to march further right, next thing you know they all no matter if establishment Republican or otherwise tried to go after that far right, NRA supporting, xenophobic, social conservative, mostly rural, mostly without higher education and in the 4th to 3rd income quintile, and mostly white voter pool.
Some will say that is the very group that stayed home in 2008 not happy with McCain, and again stayed home in 2012 not happy with Romney. I would offer this is the very group that ensured the 2012 Growth and Opportunity Project was laughed off the stage, to the point that Independents and Moderates are now in play for 2016. I just do not see anyone on the GOP stage that can sway them once they are all done in the primary season trying to pick away at whom supports Trump. If the GOP convention ends up brokered, this could be amplified where a general election strategy to gain Independents and Moderates is more challenging.
Lastly, we cannot dismiss how much party affiliation has fallen in recent times suggesting that if the GOP wants a general election win for Presidency they will eventually have to break free from the party of exclusion thinking at some point. Just the below information tells us it is going to be close in 2016, but if the GOP cannot appeal to Independents and Moderates then Hillary wins in a landslide. That could be mitigated with a Moderate Republican, but would that set up another loss just as McCain and Romney suffered? No matter what, the GOP has some planning to do and in context they should have considered the 2012 plan more seriously to reach out to the very demographics on the increase and welcomed in by Democrats.