I keep leaning towards Irresistible. Let's forget for a minute the recording's 1980s sound, the production, and the other aspects of that decade. Focusing on the bare bones of the song itself - the melody is infectious, dynamic and energetic. The song has a powerful, feel-good vibe. I think it would fit nicely in the set to liven things up the same way a track like Love's a Prima Donna does. We know Steve is an exceptional wordsmith, but on more of a strictly musical level Irresistible is a good example of his knack for writing a particularly commercial, catchy number too. That's not to disregard any other songs as many can be defined as 'catchy', but there are those melodies that have that certain accessibility right from the beginning.
I've seen footage of a Cockney Rebel gig from 1992 and the increased reliance on guitar to perform the melody rather than keyboard made an interesting variation, and one that came off quite nicely. I reckon the current band would surpass that period's display of the song, and adapt the song to a new level. I'm sure Steve must be, or perhaps was, particularly fond of the song seeing that it was recorded twice as separate versions, and also appeared on Yes You Can years later. And as a bit of trivia it remains the last song to crack the UK Top 100 discounting re-issues of Make Me Smile and the Phantom of the Opera single.