different firms suit different people, depending on their situation. the salary at first new york has to be nice, though it comes at a price - you're a slave for some other trader and you won't be trading while you're getting it. most people learn quickest by doing, not watching.
hold brothers evidently has a draw for a little while and you get to trade, which has to be the best deal out there. the price, you're locked into a contract, but who cares about that if you're getting good rates (they self clear). goldman sachs has a two year contract for analysts.
echo, bright, and andover are best suited for people who have experience, and are willing to risk their own money to trade. they obviously aren't best for newbies. since they risk absolutely nothing on their traders, they can offer you good rates.
worldco has heavy hitters and you get to be on a team who gets paid based on how you do, so has an incentive to teach you. they self clear and therefore can offer low rates. downside, supposably their software sucks, bullets on good stocks are supposably hard to get, and the nx function is subpar.
etg is switching clearing firms imminently and will now have rates that rival, if not better, rates of firms that are self clearing and those where you have to trade your own money. the plus, no money down. the minus, a lengthy contract.
it depends on your situation. i work at etg, but frankly, hold brothers seems to have the best option out there right now due to the draw and fact that they can (though i don't know that they do) offer low rates because they self clear.
one last thing: there are disgruntled traders at EVERY firm, prop firm and otherwise. my girlfriend works at goldman sachs and you would think every employee hates it by what she hears people say. for trading firms, it probably depends on how well the trader is doing, or did, to determine whether they have anything positive to say.