Depends upon what you want to deal with.  Meat means you'll be pulling heavy items and cutting them down into proportion sizes.  Not to mention the hundreds of hours you'll be spent cleaning.  I've noticed departments either get along or they argue with each other.  I found when two strangers get crammed in a kiosk all day long for years they either got along or they don't. 

In grocery, you get to deal with much more customer interaction.  Customers can range form polite to belittling you and treating you like a slave.  The last location I worked at placed us below them and treated us like a servant.  Just because the customer is always right doesn't mean they have to be an a** hole about it.  If you step one foot out of line it's all on you.  Cashiering has a couple different ways you can get fired and people try to frequently screw you up on check id for tobacco and liquor.  If you work meat you'll generally finish by 7, 8 or 9 pm.  If you work grocery you can easily do 24 hours.  In grocery you may have more shifts to pick from depending upon seniority.  If you do grocery you may be stuck at courtesy/helper clerk pay for several years until they deem you worthy of a promotion.  B.s. it's favoritism.  In meat you can immediately start working towards maximum pay raise.  Both are on different contracts so if you leave one and decide to do the other do it before you max out on the pay scale.  Your seniority will go to zero but I think your pay might be the same.  The exception is if you say for example earn $20/hr and go to meat you might max out at $15/17. 

Just depends upon what you want to deal with.  Cutting meat and people grumpy they got bad product and you're to blame.  Or grumpy customers all day long and kissing a** all day long.