If you fine TPS before the deadline of Dec 21, 2015 and receive receipt by then, you have 18 months of TPS status, that means July 21, 2017. If this time frame is sufficient to remain on TPS status, before you get GC through dependent, then you are good to go. Otherwise choosing F1 or H1B is completely your choice. None of the COS to F1 or H1B is guaranteed however. Even if you get I-20 joining school, USCIS need to approve your F1 petition and H1B quota is a lottery base.