No carrier will take care of their drivers unless if benefits the carrier to do so. They will not go out of their way, expend any time or money to see that you are taken care of, beyond that of what is good for them. Truck drivers are a necessary evil, and if they had trucks that could haul freight without having to have drivers, they'd be all over it. No matter who you sign on with, it is important to keep that one fundamental principle of the trucking business in mind. You may be leased on to a carrier, but you are out here running for yourself, never forget that.
Same with your O/O business plan. It's your business plan, not theirs, and as such they aren't concerned with it. They have one of their own to worry about.
Now, having said all that, the best carrier is the one with whom you can best work within their system to meet your goals and realize your business plan. For some that may be [insert carrier name], for others that may be you having your own authority and finding your own loads. No one can make that call for you. All of the carriers have their pluses and minuses, their warts that you have to contend with, and each and every one of of them will do things that absolutely drive you crazy. The key is finding the one that drives you crazy in a manner that you can live with, that has the least frightening warts, and has the most pluses versus the minuses.
No matter who you sign on with, learn their system, their rules and regulations, and learn them well. Once you know them, you can work within them, and use them to your advantage.
Good luck with that.