Hello everyone,

I am a long time GM of Deathwatch and am finally getting a chance to play. However, I am having trouble deciding on a character. My favorite Chapters are Ultrmarines, Dark Angels, Imperial Fists, and Carcharadons. I want to play something very group oriented so I know I probably will play a Tactical Marine for all of the Squad Mode goodies. There are so many chapters with so many good looking squad mode abilities, but which are really the best? Thank you.

Define "best".  Do you mean best like does the most damage, takes tactical control of a gun fight, or what? 

Go with whatever fits your concept and whatever is your favourite chapter. That's really all there is to it.

Otherwise every powergamer and his mother would go Imperial Fists for their psykers (+10 Willpower? Wooooo!).

I'd got with a Carcharadon for a Tactical Marine.

A Tactical Marine with stabby-stabby.

 Depends on what you want to specialize in: Ultramarines have good abilities in regards to leadership and the fact you can choose which stats to raise leaves room for some tactical flexibility, Imperial Fists specialize in defensive ability and their high WP can be very useful for a psyker. Carcharadons tend to favor stealth tactics, and intensive close combat. Think like if a Blood Angel and Raven Guard combined. Dark Angels have some good defensive abilities combined with some the heaviest firepower in the game especially the Deathwing terminator. Really it's a matter of what playstyle you like

 I'm a sucker for the Ravenwing alt rank, so my vote goes towards Dark Angels.

However, you really should choose whatever character sounds most interesting to you, more than mechanics.

I went for Space Marine Poster Child and I'm super happy with it.

I rolled up an Ultramarine Tactical Marine and just spent everything on making him the ideal leader (eventual Watch Captain very likely). So, when we go on a mission where I'm the leader - whcih almost always - our cohesiion is 12. And of course I have loads of abilities to regain cohesion. I'm having a blast "coordinating" our assaults.

yeah, what Plushy said….unless you really like to min/max yer character (and that seems unlikely as you are asking us for tips instead of already knowing what uber combo is the unstoppably bestest).  Pick something that will be fun to roleplay with your group - good stats can get tedious real quick unless that's ALL you want…usually, it's the failed rolls that make for the most memorable rpg moments.