What don't you like about Retribution? I just started playing it (finished something like 5 levels in the Ork campaign and played a few skirmishes) and I think it's great. I never played Chaos Rising.
I'm an SP-only player and I don't like the way they've done the campaigns.
The lowered RPG elements were not to my taste with the reduced level cap and new stat/abilities system removing much of the sense of achievement I had out of the game.
The between-missions 'pick a weapon or buy an upgrade for a generic squad' thing didn't appeal to me and nor did the buying squads in the field thing. Whilst that'd be a great idea for some races, it didn't wash well with me for the Space Marines, as by the end I commanded a huge army.
The whole multiple campaigns thing sounded interesting but in practice, they pulled off an awful show of it with everything feeling very "I can't be bothered to make it good so I'll just keep it really simple." When you start your second campaign, you'll know exactly what I mean because I really don't want to be a killjoy of any kind.
Additions to The Last Stand were great and multiplayer sounds good, especially after they worked out the early Steam matchmaking issues.
They also chose a bad DLC route. Pay us money for skin packs or some extra items in TLS. Whilst the items might not be 'too bad' a price for more flexibility, the skin packs are a ridiculous price for what they are.
Chaos Rising contained one fully fledged Space Marine storyline, continuing on and improving greatly from the original DoW2 campaign, and set things up for a really great finish to the whole thing. The final boss fight was horrific, especially with the crash bugs, but the campaign was memorable and had replay value beyond different squad load outs and stats.
Retribution was a step back, making it worse than DoW2's original campaign (imo)