Since none of the builds listed here fitted me, I decided at lvl41 to buy a skill reset, reset my skills and follow my heart. This is what I've used until lvl50: http://dn.duowan.com/2zmnq/?wV0f4Wy1BVpf7OfR2upw2Yv|207$258$45&ifr=guardian.html
Very nice build for levelling, and it gave me quite a few satisfactions along the way (coupled with 45b life equips).
Sadly, lv50 arrived, and with it all the new mess that makes the tank far less tank that it was before (until most of the LM dungeons you can basically be invincibile 100% of the time by rotating the skills), so I had to adapt.
This is what I've started building now:
Shield blow: very good damage growth and low cd. At lvl15 it was critting for 18k clean.
Block: maxed in the previous build, but kept at 7 for the moment, since I still have to understand how much I actually need it for endgame nests tanking.
Kicks: maxed in the previous build (since the damage growth is acceptable, plus kicks are the spammed attack, so the damage increase over time becomes significant. each holy kick was critting for 12-13k clean when maxed [6-7k at minimum]), kept at minimum here, since I still don't have enough information.
Sliding Step: maxed. No explanation needed.
Sliding Knee Kick: dropped in the new build, since most of the bosses and mobs can't be juggled anymore, so it's not that useful in pve anymore.
Heal: maxed. Saves my ass and the ass of my party members quite often.
Aerial evasion: maxed in both builds, since I need it quite often, and the lower cd is critical for me.
Damage reduction: maxed. The less damage the paladin takes the more useful he is.
Max HP: More health = more survivability, which is the main point of being a tank.
Max MP: maxed before (since I always run out of MP) now kept at minimum, since I don't know the requiements for SDN, and in bishop the mana used wasn't that high (especially since I kept being hit and my mana hat kept replenish my mana).
Mana Regen: critical. Maxed.
Healing boost: taken it, since it's 0SP, but it's mostly useless, or so it seemed to me when I used it.
Provoke: maxed (+crest). No explanation needed. This is the skill a paladin should spam the most.
Armor Break: maxed, for debuff and good damage.
Shield Charge: 1 lvl, since the growth is low, and it's mostly useful for covering big distances fast and for aggro.
Autoblock: lvl8. Minimum necessary for Autoblock EX. No point going higher.
Stance of Faith: godlike skill, IMHO. Was maxed in the previous build because it was able to stop all attacks from both mobs and bosses (except for freezing effect and sometimes for electrical shock effect). In the new abyss dungeons and in endgame nests seems to be far less useful, since the bosses simply pierce through it or ignore it, so the paladin is forced to avoid and stay mobile, sadly. So for the moment it's on minimum. Gonna see if there is need to bring it a little higher later, since I love it.
Air Block: Useless. Upgraded only for the next skill.
Divine Punishment: Maxed. Damaging the bosses with their own attacks has no price!
Iron Will: damage reduction is now capped at 80%, so no real point in maxing, especially since it's not possible to reach Divine Punishment's cooldown, so I just kept it at minimum.
Avatar: aka Godmode. Amazing skill. Needless to say it's sadly becoming less and less useful against bosses, since both Serpenta and Bishop can clear it (silence&breath) or pierce through it (that damn light attack). In any case useful in a lot of situations. With duration crest.
Auras: more or less useless while levelling, but critical for SDN and Bishop. Maxed, since they will be needed to keep myself and the party alive, and to buff the DPSers dealing light-property damage.
Autoblock EX: name is pure troll, since it's not an improvement of autoblock, but a completely another skill. Still, the buffs are quite useful, and they stack with avatar, for more damage (yes they stack with saint's buffs too).
Guardian Force: maxed, to have more damage absorb from the bubble. Useful, but depends heavily on when and where used. 16k damage can be taken in a single shot from some bosses, so pay attention to it.
Guardian Crash: amazing dps skill. High cooldown, but very nice damage. With skill ring.
Generally, what I've done here was drop the magic tree entirely and go full physical spending all the points I could in my defensive skills (dropping the magical tree until smite gives 80+ SP to spend in more useful stuff), so I could be a full tank. Everything went pretty well and smoothly until I had to do the heavy stuff, and my nose got crashed by the attacks that ignore paladin's defensive skills, forcing him to stop tanking and start avoiding like other classes...
But I still don't wanna drop my defensive skills for DPS. I'm a tank at heart and I'm gonna find a way to be able to tank the most stuff I can and laugh in bosses' face.
Enhancement crests: vit,maxhp,def,mdef,str,atk,mpregen,crit, all with crit third stat (phys atk on the crit one)
Skill crests: epic kicks' crests, blue crests for godmode and provoke.
Gear: still working on it.
Props to Goat and trunet for their builds, from which I've taken some things (like the non-maxed block and the non-maxed autoblock), and props to Fox, Kaziziz and trunet again for their patience in answering my questions. Thanks, guys.
P.S: It's HEAVILY Work In Progress, so it will be changed a lot, probably.
P.P.S: This is just how I see the paladin. If you like my ideas follow them, but not blindly. Think with your own head.
P.P.P.S: Suggestions and critics are welcome!
EDIT: Temporarily using Ladder build atm: http://dn.duowan.com/2zmnq_unlock/?w11tZ2xAXHnqx2HFz0Ixn8T|140$325$45&ifr=guardian_unlock.html