I started gearing another FDK like month ago...
Armory: "Aggramar".
I was doing fine with Strength gems at start, but, after i started getting ICC items i gemmed them with Arp, even tho i had barely 500 at first (since i didnt want to waste gold on regeming).
Strength gems are kinda better, untill u can reach 80-90% Arp with T10 2/5 bonus and with Sigil of Awareness.
But again, nothing of that will matter if u dont learn the rotation right and if u prio Frost Strike over Obliterate.
Have in mind that im in a good guild and that i know my ****, so getting in raids and getting gear is not a problem for me, if u pug, u might want to gem Strength right away, since god knows when will u get ur next item.
Also, i had A LOT of BoEs crafted when i started...
ToC chest and wrist, ICC legs and boots, trash neck and ring, Coined Havoc and DBW, since i got STS normal fro RS 25m... Im saying this so you dont go and try to copy paste me since i probably have better conditions than you.
All in all, try them both i guess.
They are both needed in raids equaly, get a two hander and two one handed weapons, get dual talent specialisation and try them both.
They can use the exact same gear with strength gems at start, just swap weps when u swap spec. See which one does more dps and go for it. Once u get more gear, test both again and go for that spec...
P.S. Frost is currently bugged from what i know.
Pestilence, while using Glyph of Disease, on single target wont refreah Icy Talons, and your dps will suffer by a lot cos of it.
Bug is reported and it will get fixed soon hopefully.
Untill than use the same Glyph and try to pestilence on 2+ targets whenever u can.
If there is only one target, simply use IT and PS to apply diseases and refresh Icy Talons.
Its a pain in the ***, you will do less dps, but its kinda fun since u have to think about things before you do them, and probably set them up while positioning or something... :D
Edit1:
Https://www.warmane.com/bugtracker/report/69364
This is the report if anyone is interested in the details.
Read the comments aswell.
Edit2:
It is fixed. Just checked it.
Glyph of Diseases and Icy Talons are working fine.