Which do you prefer and why? with both installed will they work well together and compliment one another or is it best to choose one or the other?

They both work exceptionally well together...if your system can handle the load. I'm using them together since this season.

I recommend using it with Frostfall, Real Needs and UFO. Maybe a journal mod and immersive Armor/Weapons.

I prefer Immersive Creatures. I think SIC adds enemies in a much more tasteful and immersive manner than Monster Mod. Not only that, SIC is configurable, via an MCM menu. Monster Mod is not. With SIC you can specify which enemies the mod adds to your game, how they behave and how strong they are. There cool little extra features like Ore Golems that spawn when you mine or Spiders that emerge when you loot egg sacs. I can't say enough good things about this mod. I have played all of the creatures mods that have been created for the Elder Scrolls since Morrowind and I think Skyrim Immersive Creatures is the best.

If you do decide to use Monster Mod: I would not even consider using that mod without jackstarr's lore version. Jackstarr's version removes the dinosaurs and all the other non-Tamriel monsters that constantly remind me that I'm using a mod every time I see them.

With SIC I use http://www.nexusmods.com/skyrim/mods/11836/? and the http://www.nexusmods.com/skyrim/mods/32394/? by lifestorock. This adds random hostile encounters which, again, you can configure via a MCM menu. You can configure how often encounters happen, decide who you encounter and decide how strong they are.

I also often use http://www.nexusmods.com/skyrim/mods/27866/? by Dalquist. This adds new enemies, starting at level 10 and scaling right along with your character indefinitely.

Isn't high level enemies automaticly included with skyrim immersive creatures mod now?

Also with the monster mod doesn't it also add new dragons that would conflict with the deadly dragons mod?

@Pseron Wyrd:

Always a pleasure to read your SIC related comments.

@Soulmancer:

SIC and HLE work complementary. You are right that SIC uses a similar high level system than HLE. But it doesn't work for Bandits, Thalmor and other non creature enemies.

As Pseron Wyrd mentioned use jackstarr's replacer for SkyMoMod. As far as I know he also offers a no dragon version.