Most boring possible Republican primary

[Angel of Death]

Who's most likely to just run away with the nomination from the get-go and provide the least entertainment in the process?

[Mehmentum]

Walker could manage it if he's very lucky, he could paint himself conservative enough for the base, but a governor of a left leaning state.  Still, I don't think he'll have a smooth path even if he becomes the frontrunner.

Cruz would have the most contentious path.  The establishment would throw the kitchen sink at him if he won Iowa.

Paul would also have extreme opposition due to his libertarianism, both conservatives and establishment types would be dissatisfied.  A more conservative candidate would definitely put up a strong challenge if Bush is the frontrunner, with his positions on immigration and education. 

Christie is very weak in the south, so again, a conservative would likely challenge him, though he's in a much better situation than Bush.  Huckabee would be the ideal opponent, as he plays very well in the south.
 

[BaconBacon96]

Romney runs again and sweeps all the early contests, leaving just him and a couple of conservative challengers.

[© tweed]

Jeb vs. a cast of crazies and fools.  ie Rand Paul, Ted Cruz, etc.  he'd have the moneymen in the bag if Walker, Christie, and Romney sit out.

[Likely Voter]

There really is no chance of someone running away with it. Even in past years with heavy favorites they never sweep the early states. There always seems to be some challengers who pick up some pre-Super Tuesday states, like Dole and Robertson in 88, Buchannan and Forbes in 96, or McCain in 2000. 2016 is shaping up to be the most open GOP primary ever with no heavy favorite or 'next in line' candidate.

[Mr. Morden]

There really is no chance of someone running away with it. Even in past years with heavy favorites they never sweep the early states. There always seems to be some challengers who pick up some pre-Super Tuesday states, like Dole and Robertson in 88, Buchannan and Forbes in 96, or McCain in 2000. 2016 is shaping up to be the most open GOP primary ever with no heavy favorite or 'next in line' candidate.

The 2004 Democratic primary looked extremely unsettled early on.  No one would have predicted that Kerry would sweep virtually everything (I know his challengers won a few states, but Kerry still won 46/50 states, and it was pretty much over when he won both IA and NH).  While it might be unlikely that the 2016 GOP race will play out like that, it's not impossible.  Ideally, you want a candidate with some potential to win both IA and NH, who the party establishment is OK with, yet who isn't really doing that well early on, but surges at just the right time, before IA and NH.

Walker is an example of someone who might fit that bill.  Not saying he'll do that, but just throwing it out there as a possibility.

[Mister Mets]

I think it's definitely possible for someone to emerge in a crowded field, and stay the frontrunner largely due to the positive press that comes with being the frontrunner as undecided voters decide they don't have particular reasons to not support the guy.

It could happen with the right kind of establishment player, a Marco Rubio, Paul Ryan, Scott Walker, John Kasich, Mike Pence or Rob Portman.

For a variety of reasons, Jeb Bush, Mitt Romney, Chris Christie, Rand Paul, Mike Huckabee and Ted Cruz would have too much opposition to avoid a competitive primary.

[Likely Voter]

On the GOP side there has never been a candidate that won both IA and NH (Romney had been declared winner of IA in 2012 but was later revoked and he was a fave son in NH anyway). In the modern era the closest thing to someone 'running away' with it was Bush Jr. in 2000, but still McCain was able to win 3 pre-Super Tuesday states (most important of which was NH).

Things can certainly get boring after Super-Tuesday, but I think it is impossible for 2016 to get settled down to that level before.

I am not saying there can't be a front-runner, but I was responding to the 'running away with it' premise of the OP.

[Absentee Voting Ghost of Ruin]

CPAC gets hit by a rogue meteor. Due to having skipped it, Jeb Bush is the only first- or second-tier candidate not dead or seriously injured.