The 16v four pot is ok. It's quite rev happy, so presses on, especially with the manual box.
Obviously it lacks the grunt and smoothness of the V6 but it gets the job done 
The 8v is best avoided... It's not upto hauling the Omega around.
I think the 2l is a shade underpowered (talking about the 16v ones, the 8v are thankfully as rare as they are hopeless), the 2.2 is just about "good enough" in manual trim, but seems unsuited to an autobox*.
I seemed to recall many journeys of fun** raging the nads off tunnies old 2.2

*The one exception was auto addicts 2.2 auto that for some reason went like a scalded cat (relatively speaking), by far the best 2.2 Omega I've ever driven.
**In that "I mustn't slow down for corners, as it takes too long to get back up to ramming speed" mentality. Which was always "interesting", given Tunnie's love for that American style of worn out, knackered, detached suspension.