Between the two listed, I prefer MM just for the range. I've had people say it's not that much of an issue, right up until you face an enemy at 11-20 squares away, and then boy do you want MM.
Slowed is a pretty marginal condition. If there's an enemy 5 or more squares from any ally, and no ally moves up to it after it's slowed, you've saved the party an attack. It's handy for slowing down a fleeing enemy at the end of a fight. It /should/ be good against skirmishers, but too many of them have movement powers that aren't based on their speed...But after playing two sessions and more careful reading, I fail to see the MM's advantage over Ray of Frost save range. The slowed ailment more than makes up for that in my eyes.
I agree with this. Unless your monsters are running all over the place, slowing them really won't help much. In actuality, it may be a bad idea in forcing them to stay and whomp on the tanking healer because they can't reach anyone else.I always found slow to be a weak condition on its own.
It isn't a super useful condition. OTOH the more different options you have, the better your control is going to be. You may find slowed is useless in some fights, and marginally useful in others, and once in a great while really good. I think you'll find the same is true of most low-level effects though. Immobilized for instance is nice (and plainly stronger than slowed) but fairly useless if there's a PC in range of the immobilized creature when its turn comes up. All you can really do is pick up a range of control effects and see what will work in a specific situation.I agree with this. Unless your monsters are running all over the place, slowing them really won't help much. In actuality, it may be a bad idea in forcing them to stay and whomp on the tanking healer because they can't reach anyone else.
There are cases where it may be useful, however, such as if you have a rogue with the feat that they gain CA against anyone who is slowed.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.