Considering I've fairly recently gone through a real-world situation where I had to do something like this (this was before TFU... and it certainly wasn't only 50, but it was still hard!), I can pretty much just edit the list of what I did take, adjusting for TFU:
1. Grand Admiral Thrawn
2. Darth Vader, Jedi Hunter
3. Raxus Prime Trooper
4. Admiral Piett
5. Storm Commando
6. Admiral Ozzel
7. General Veers, Hologram
8. Evo Trooper
9. Emperor Palpatine
10. General Windu
11. Mas Amedda
12. Qui-Gon Jinn, Jedi Master
13. Jedi Weapon Master
14. R2, Astromech
15. Yoda
16. Obi Wan, Force Spirit
17. Chewbacca, Rebel Hero
18. Golan Arms DF.9 Anti-Infantry Battery
19. Han Solo in Stormtrooper Armor
20. Luke and Yoda
21. Luke, Hoth Pilot Unleashed
22. Wookiee Freedom Fighter
23. Yoda of Dagobah
24. Princess Leia
25. Han Solo, Scoundrel
26. C3P0 and R2
27. Ugnaught Boss
28. Gran Raider
29. Boba Fett Bounty Hunter
30. Aurra Sing
31. Aqualish Assassin
32. Garindan
33. Jango Fett, Bounty Hunter
34. Lobot
35. Boba Fett, Mercenary
36. Lando Dashing Scoundrel
37. Muun Tactics Broker
38. Wicket
39. Ugnaught Demolitionist
40. Dark Hellion Marauder on Swoop
41. San Hill
42. Bodyguard Droid
43. Battle Droid
44. Aurra Sing, Jedi Hunter
45. Jaina Solo
46. Mara Jade, Jedi
47. Nom Anor
48. Advance Scout
49. Exar Kun
50. Darth Bane
What I added to Boris's list:
Admiral Ozzel: The Imperial San Hill, but Ozzel/troopers is it's own squad, and all the other pieces are there.
Yoda: I do still love this piece.
Chewbacca, Rebel Hero: Always handy if you have the points.
Golan Arms DF.9 Anti-Infantry Battery: My current favourite piece in the game.
Princess Leia: I think Boris must have simply forgotten to add her
Gran Raider: More options for the Nom Bombs component, 4pt gambit grabbers with Stealth are always nice.
Garindan: One of my favourite Lobot buys if I can afford the activations, and there's nothing else I need at the moment
Jango Fett, Bounty Hunter: I just love seeing this piece on the board.
Boba Fett, Mercenary: A very different Boba over BH, I do like this piece.
Wicket: Another favourite Lobot buy.
Dark Hellion Marauder on Swoop: It's what makes Exar Kun an interesting option. I'd have dropped Exar if I couldn't fit this.
What I dropped from Boris's list:
General Veers: Good, but not *essential*. Veers didn't deserve 2 slots.
Probe Droid: Again, good but not essential.
Darth Vader, Unleashed: I was never much of a fan, but I did want to see a second Vader up there.
General Kenobi: Not much of a fan.
Queen Amidala: Only benefits 1 piece, not worth it in my 50.
Princess Leia, Senator: Most squads would sooner take Princess Leia these days.
Obi Wan Unleashed: Eh...
Twi'lek Bodyguard: OK, I would have liked this to stay, but it's only 50.
Boba Fett, Enforcer: Same as above, and I already have 2 Bobas!
Bith Black Sun Vigo: Great piece, great option to have, but I often find myself taking Lando DS over the Bith these days
Talon Karrde: Another great piece, but since the NR has the MTB engine available in my 50 the Recon isn't so important. Disruptivr would have been nice.