I don't accept the premise of your poll choices.
I think the pace of the game should be increased, but I don't think you need a clock to do it. Rules already exist that put
limits on time between pitches, and make it illegal to step out of the box unless you took a swing at the previous pitch. If MLB told the umps to enforce those rules, you wouldn't have anymore 4-hour Red Sox-Yankee games. (I swear, the Red Sox are the worst at wasting tremendous amounts of time between pitches.)
Just look at a game from the 1970s or 1980s on ESPN Classic sometime. The pace of those games is phenomenal compared to today - and those games were obviously televised, too, so you had the same issues of ads between innings. Pitchers took the sign and threw the ball; batters stayed in the box. We could still do that today, if the umps simply enforced the rules that exist.
As a youth baseball umpire, there's little worse than having a team of 12-year-old "superstars" who think acting like the knuckleheads they see on TV is cool. Take a ball; step out of the box; check for the sign from your coach; rearrange your batting gloves; take a couple of swings; start to dig in while you're holding up your hand expecting me to hold up the pitcher; take a couple more swings. I tell 'em to stay in the box, or I will let the pitcher throw anyway (I know I'm supposed to assess a strike instead, but this is more fun).