The only BG alliance has even a chance at is AV.
Every single...and im not kidding...EVERY single AB, 4-5 cap loss. Every WSG, farmed at GY.
1.5x honor doesnt even come close to making up for the amount of losses alliance have. 40 AB marks for that piece of gear? Have fun getting spawn camped for 40 games.
If you plan on PvPing, dont make an alliance character. Take advantage of the open horde creation and make all your alts NOW!
Of course, there will be some guy coming in here say "You are just a crybaby, alliance pvp is fine." That guy is a liar. He is full of ****. Probably a horde player trying to boost alliance participation to lower his horde queue time.
Would you rather sit in a 20min queue on horde for a 99% chance of winning and getting 3 marks, or have 1-5min queues on alliance for 99% chance of losing and getting 1 mark and 50-100 honor, while horde get 200-250 honor for GY farming you?
Just go horde.