I chose the BOS as there goals lined up to mine (lore wise), i mean sure the institute is awesome but the have no scientific ethics such as kidnapping the people of the commonwealth and (possibly) experiment on them with the FEV virus. that's what made the institute less appealing to me. the minutemen were kinda too good to be true type of deal there ideals were noble and all but unrealistic. the railroad wants to save synths (personally i do and don't agree with them). the BOS were more realistic to me, their goals were confiscate technology ( although they end up killing innocent people, and taking anything and everything that is considered dangerous: with a little reformation it could work out). although Elder Maxson was kinda hitler most of the time, he knew that synths were dangerous to mess around with as making a synthetic human being could cause real problems as they have their own will which means they could easily wipe out the human population. at the end of the day all the factions are neither good or bad.