A lot of good tracks to choose from. I guess if I had to pick one it would be "Strange Frontier", as I have a weird affinity for the vaguely apocalyptic. Similarly, I think "Beautiful Dreams" is terrific. But I also love most anything off of "Fun in Space". "Magic Is Loose" is classic especially.
In my opinion, Airheads,Strange Frontier, Man On Fire, It's an Illusion, No more Fun. I'm not too keen on Fun In Space (crap production) or Happiness? (too mellow). Mad Bad and Dangerous to know is the best Cross Album is too poppy and Blue Rock is patchy.
Lots of good uns, but Pressure On is a fabulously written pop/rock song with fantastic lyrics and great melody and uplifting chorus - would have been a bit hit if sung by someone else I guess.
Old Friends is also a fitting tribute to Freddie. and I do like the laid back blues groove of Everybody Hurts Sometime
Anything off of Fun In Space, especially Future Management, I'm starting to really like most everything off of Happiness and Electric Fire. Strange Frontier isn't bad, either. I'm really getting into The Cross stuff a lot too especially Heartland, Shove It, Feel The Force, New Dark Ages, Contact.
And you can't forget Two Sharp Pencils.