Danielle,
I would definitely stay away from synthetics if you can. Bio-identical is a poor label but often used it should be labeled Bio-mimetic.
Pills (take sublingually if able to)
Pro: Cheap, many people use it
Con: Spurts of hormonal spikes, overworks/toxifies liver over time (this varies person to person on when harmful to liver), most medical complications with regards to blood clotting factors, remember to take 1-3 times daily.
Creams/Gels
Pro: Absorbs into bloodstream, fast acting, bypasses first pass on liver, less complications with blood clotting factors.
Con: Remember to take 1-3 times daily, not high enough concentration for my purposes (pre-SRS), but may be viable option for you, hormone spikes.
Patches
Pro: See Cream/Gel, also only change every 3 or so days, more steady hormone levels.
Con: Not high enough concentration for pre-SRS or if skinny, may be a very viable option for you.
Injections:
Pro: Only need to do every 2-3 weeks I think, goes into bloodstream, bypass first pass of liver, very safe in terms of blood clotting factors
Con: Cost, hormone spike and fade away effect,
*Note: I haven't really looked into this much, don't like needles so I didn't consider it an option for me.
Pellets:
Pro: Only need to change 2-4 times per year, absorbs to bloodstream, bypass first pass of liver, virtually no complications due to blood clotting factors, very steady level of hormones.
Cons: Costly (insurance most likely will not cover, though in long term about as same as injections), bruising around incision, careful of bathing for 2-3days after incision, can't exercise for at least a week after insertion, if performed by someone with little-no experience can have protrusion or rejection.
*Note: Method I've chosen to go with, have had no complications thus far.