I have/had every single SW Attakus statue on the market, so I feel qualified to give you an answer based on that.
Today the only ones I don't have anymore are the new Trilogy ones(Maul, Padme etc)
My top 3 are:
1-Vader 1
2-Jabba
3-Vader 2
If you want to have just one and only one(even tough I doubt you will resist), then get Vader 1. If it's too expensive for ya, then go with Vader 2.