Let me start by saying I'm definitely no expert and I know this is nothing groundbreaking or new, but I've tried a whole bunch of the most popular and common gear builds and have finally landed on one that I am really happy with.
So far, it's the best combination of high MF and killing speed that I've used yet so hopefully my trial and error can be helpful to others looking to build an effective MF light sorc.
Weapon: Oculus + Ist
-Pretty obvious choice here. Hoto is very popular b/c of the 10% more FCR and higher resists, and I've tried several variations using it... but you just lose so much MF for virtually no gains
Shield: Spirit Monarch 35 FCR
-Explains itself, only real alternative is stormshield if you're going for a super safe DR build which isn't really needed
Armor: Chains of Honor
-skills, high resists, decent defense, and 25% MF. Beats enigma in this build b/c of the resists
Helm: Griff's + Ist
-A 5/5 Facet is ok here too, but with a ~38-40k lightning you'll still plow the broken LIs with 18-20ish -ELR and 30MF is 4 slots worth of inventory space in SCs
Amulet: Rare with 2 skill/7+ FCR/(useful mods FR/life/mana/str/MF)
-If you can't find a decent amulet, mara's + a FCR ring can hold you over
-Easy choice, skills and FCR breakpoint
Gloves: Chance Guards
-Easy choice again, huge gold boost and upwards of 40% MF
Rings: 2x SoJ or 2x Nagel
-Choice here depends on how much you like chugging mana pots and if you need more dmg for 3+ player games
Boots: War Travelers
-Easy choice again, upwards of 50% MF
Inventory: the obvious torch/ani/gheeds, then adjust MF SCs vs light GCs according to how much killing power you need (high player games, 8 player baal runs? add more light GCs). Use full MF SCs for solo games b/c you'll still have 30k+ light dmg and wreck everything without skillers. You may have to run 2-3 11FR SCs if your FCR amulet or ring doesn't have FR on it.
Merc: Infinity, treachery (or fort if you must), andy's
-Easy choices here...
So basically what this gets you is anywhere from 225-300+ MF from gear alone (upwards of 350-400ish with gheeds/SCs), some -ELR for broken immunes, 117 FCR breakpoint, solid life/mana, and high damage output.
Have tried full tal's, Hoto builds, shako builds... and they all have issues. Full tal's builds require 2x FCR rings to hit the 117 breakpoint and end up lacking in mana/killing speed vs others, Hoto builds have too little MF without any notable increase in killing power, shako builds lose -ELR and make killing broken immunes painfully slow (no-no doing pits/AT/chaos).
edit: quick disclaimer.. I know that you can MF with lesser gear, budget gear, and such. I am just posting the most "optimal" setup that I've come across yet which takes a couple weeks into the ladder to get into. For the record, I started the ladder with a blizz build using rand gear until I could afford to move into a light build (infinity).