Independent lawyer or law firm?

There should be no disadvantage, it all depends on how good each lawyer is. You may find out the price by asking them how much they charge.
There is no telling which one is higher or cheaper, as people's decisions to establish their fees are not in relation to whether they are independent or not. They all charge per hour, as far as I know. You might want to look for someone who is effective in producing results and efficient with their hours, however, there is no telling if that person may be providing services as part of a firm or on their own. The best way is to consult them and form an opinion about which lawyer you would like to hire, regardless of their practice status.