You're in a rough spot. The way rain jackets work is that it has to be humid inside your jacket to push your sweat out of the waterproof barrier. If it's too humid outside, it won't work as well. So in FL, at those temps, you're pretty much guaranteed that the material won't "breathe" like any of the companies claim and you will get clammy inside.
So you mitigate this issue you want as much ventilation (not the same as breathability. Breathability is the property of the fabric itself to let moisture escape. Ventilation is options that increase air flow like pit zips or pockets with meshing). The best bet in constantly wet and humid environments is a Poncho made of plastic or silnylon. The loose fit lets a lot of air in and out so that your sweat leaves your body, but you aren't soaked from the rain. Next up would be probably driducks which breathe very well. They're incredibly cheap but not durable if you aren't careful (good for trails, terrible for bushwhacking). Then you have normal jackes. eVent probably breathes the best of modern fabrics but it's still a marginal improvement.
Personally I'd say expect to get wet/damp and just focus on how to stay warm in those conditions! That will be far easier to accomplish than trying to stay dry =P
REI has a phenomenal run down on the terminology here:
http://www.rei.com/expertadvice/test/rainwear.html?s_tnt=42401:2:0
But this is my loose interpretation to get you started.
Hardshell: completely waterproof. No water will come in from rain. Some are breathable (goretex, eVent) which means in certain situations they will let your perspiration evaporate. Some are not breathable (plastic, silnylon) and will always be humid/clammy inside. Seams are sealed so that water will not seep in.
Softshell: Not fully waterproof. Has a treatment (DWR, aka durable water repellent) that will cause water to bead up and roll off instead of soaking the material. This treatment eventually fails in sustained rain. Depending on treatment, dirt, type of rain this will last from 30 mins to 2 hours. Generally not made with a WPB fabric so they will let your sweat evaporate. Designed for aerobic activity where minimal rain protection is necessary (think climbing mountains with brief afternoon thunderstorms). Usually has some stretch and often with a thin fleece lining. Once wet they stay wet for a long time. Usually heaviest option and least flexible for overnight trips (AMAZING for day trips though).
Rain Jacket: Can be used for anything to protect you from the rain within the industry sadly. Usually people think of hardshell=rain jacket.
Windshirt: Not waterproof. Thin/light fabric. Has a DWR for some water resistance, will eventually let rain in though like a softshell. Very good at cutting wind which can be more chilling than just cool air temps. Probably not so useful in forests as on open plains or mountains (not sure what type of environment you hike in most). Fairly breathable…they are in essence a "softshell" but get their own distinction for being so light weight and versatility. (Check the latest article about wind jackets that gives an overview/history).
