I am playing TK Ranker atm and used to play SG a long time ago. As for equipment, I would say that Mythical Lion Mask has proven to be quite useful to me. It adds some DEX, chances of stun, and ATK depending on the refine rate. It also has a slot. Only bad thing is that it uses both upper and middle slot, so if your server has implemented the Sunglasses[1] quest, you might wanna reconsider if you want a +STR upper headgear along with a card in upper+middle. My Ranker has high AGI because higher ASPD makes kick spamming faster (at least in my server). I use Falcon Muffler, Freya's Shoes, Odin's Blessing combo and a Stone Buckler. These were equipment that nobody used in my guild, so I decided to keep my character cheap. As for cards, with these equipment I use Grand Peco + Peco peco Card on headgear + armor; racial reduction cards on shield; Mantis on Rings. Might not be the uber equipment everyone is looking for, but it gets the job done.
For alternatives, you can start searching on Items/Armors/(whichever you are looking for)/Job: Taekwon/Star Gladiator. It will show you all the available equipments for your class. Valkyrie Shield might be better than Stone Buckler (if it is easily attainable in your server), Glittering Jacket/Divine Clothes/ Goibe's Armor with Peco peco for extra HP, (I don't know if your server allows the class to use "Every Rebirth Job except High Novice," but mine doesn't, so I'm just going to put "Every job expect novice" equipment) Boots[1] with Matyr if AGI/Green Ferus if VIT. This is the only stuff I can think of right now. I'm not saying this are the ultimate equipment for the class, but they are equipments that worked for me so far.