With the changes brought about by 5th edition Troops are very necessary. I'll admit in piror editions, I took the minimum amount of troops that were required. One edition allowed a squad of 3 Rangers as a Troop choice. Six figures filled out the whole two squads of troops. Now that 2/3 of the games depend upon grabbing and holding objectives with Troops, haveing solid units for troops are a must.
Eldar on the whole are a very fragile bunch. Toughness 3 across the board. However the Wraithguard are another story. Their Toughness of 6 and their armor save of 3+ makes them a very sturdy unit. Put in a Warlock, and you don't have to worry about their wraithsight weakness. Give the warlock the Conceal power and they will get a mobile 5+ coversave. Throw a farseer next to them with Fortune...letting them re-roll their saves and you have the toughest unit in the game to move off an objective. Just keep a Close Combat unit nearby to help incase they get swarmed.
I had 5 Wraithguard painted up, but they only count as troop chioce if you have 10 in the unit. You will find through all three of these Army Projects that I am a cheap bastard when it comes to gaming. I'm not about to dish out $50-$75 for 5 minis. You really need a plastic Wraithgurd box GW. Anyway...I had some of the really old Epic Eldar Knights, and one of the ancient Eldar Ghostwarriors. They are close enough to the Wraithguard that i painted them up to finish the unit.