I've played both Holy Pal and Disc at this level and at higher levels during my P2P days and my observations:
Cutting the bubble duration from 30 seconds to 15 seconds (to match the weakened soul debuff) hurts Disc quite a bit. You can't cheese back-to-back bubbles like you used to. This was pretty useful especially when you had rogues beating on you.
Disc has a larger mana pool but also goes OOM faster, and once OOM in combat a Disc basically has nothing, while an OOM Holy Pal can basically always cast Holy Shock and follow it up with Word of Glory.
Disc can use Shadow Word: Pain on rogues and ferals to prevent easy restealthing, Holy Pal has nothing comparable.
The Fortitude buff is pretty huge at this level. The average F2P player probably has around 1200 health, 18 stam represents roughly a 15% health increase. If you have a priest(s) that are smart enough to rebuff Fort during the BG it is a pretty big advantage against a team without a priest.
Holy Pals can take a real pounding vs melee, a priest with bubble down/purged is a sad squishy thing. BoP and LoH are on fairly long CDs but add a bit of value when used properly.
A Disc can take down someone low on life from 30-40 yards, while a Holy can't.
Disc can put out better pressure with Holy Fire - Mind Blast - Penance than a Holy can with Exo spam.
Fear CD is half as long as HoJ, can hit multiple targets, but breaks on damage. Fear can also pull a nearby unseen rogue out of stealth, while a Paladin has no similar AoE.