Missions & Complexes

You can actually find Lvl 4 Security agents for all four empires within a dozen jumps of Jita in Caldari and Amarr space. Domain has a Quafe agent, some Minmatar and the Forge has SoE, Caldari, Minmatar. Lonetrek also has Natura Agents for Amarr.

Basically if you really wanted to you could run missions for all of them and watch your standings. I recommend SoE if you want to be friends with all though.

I will reveal some trade secrets. I'm doing L4 for Nurtura in Isseras. It's a 0.6 system and they have 2 L4 agents in the same station. It's 4 jumps from Jita.
The Nurtura LP store has good items for LP -> isk conversion. I am now using mostly INEANM, although the sell price has been going down. The only problem is standing if you're doing storyline missions (ie, losing standing with Minmatarr and Gallente).
Mission wise, I get mainly Gurista, Blood Raiders and Sanshas (and those damned drones). I use a NRI or a Rattlesnake for clearing the pockets. The RS has a good sensor strength, I use it against the Guristas (Gecko + scourge cruise). The NRI I use against BR/Sansha/Drone (Mjolnir cruise). The RS has more punch, but the NRI is more flexible in terms of engagement profile. The RS fit I use is Gecko based, not sentries, I don't like the static nature of sentry boats.

godamnit, why =/

Minmatar. Because Republic Fleet Warp Disrupters yo! Since your rival is Amarr, your level 4 missions should net you a lot of those Smash the Supplier missions which = lots of tags.

Looked at some items, here is a bit of statistics.

Neural boost standart cost on the market 20.5 mils., to get it we need 12 mils + 12000 lp. Our profit at the end is 0.7 mils for 1000 lp.

CN ballisic control cost on the market 94.7 mils, to get it you need 45 000 lp + 18 mils + tags worth 50.3mils. Our profit at the end is 0.56 mils for 1000 lp.

CN em ward field cost on the market is 28 mils. to get it you need 11250 lp + 4.5 mils + tags worth 12.6 mils. Our profit at the end is 0.96 mils for 1000 lp.

CN invul cost on the market is 419 mils. to get it you need 180000 lp + 72 mils + tags worth 202 mils. Our profit at the end is 0.8 mils for 1000 lp.

Raven navy issue 0.73 mils for 1000 lp.

I have always found the most consistent LP/ISK ratio to be SOE. SOE ships and probe launchers tend to average about 2:1 month in month out without huge fluctuations. I sold 4 sisters core probe launchers about 30 minutes ago for 40 mill each. They cost 14k LP and about 11 mill in cash and parts to buy from the LP store. That is a return of just over 2 mill per 1000 LP.

Note that SOE rarely ever give the huge returns some corps occasionally give you (my best ratio ever was 300 mill ISK return for 60 mill LP for a single mining implant from an Amarr corp ) but SOE rates never drop to the crap returns you get from the various navies either.

As I stated above, all empire factions have agents within 12 jumps of Jita, SOE also does. They are all highsec. Look east, little north, east again and you will find the error of your statement.

Using a Rattlesnake, you'll probably find your best opponents in Amarr space. Sansha turret disruption means nothing to you, and the 'Snake has enough tank that EM damage isn't a huge inconvenience. Second best is Angels - you're shield tanked, so who cares if you're target painted?

SoE give good, consistent LP/ISK returns. HOWEVER: the advice about SoE liking everyone posted above is INCORRECT! SoE give positive standing with Gallente, Minmatar, and their friends, and negative standing with Amarr, Caldari, and their friends, with Gallente and Amarr being the primary +/- factions. All level IV SoE agents, regardless of location, give lots of anti-Amarr missions, meaning that, if you accept them, and run the storyline missions, too, you can rapidly find yourself having problems traveling around Apanake, and very near having issues around Osmon.

Look up DeMichael Crimson for some very good advice regarding standings.

A nice balance might be to run for SoE in Minmatar space, and then for either Amarr Navy or Khanid Navy.

Try to not accept anti-faction missions, if possible.

Good luck!

Most likely SoE in Minmatar space. Min-maxer mission runners tend to concentrate in Minmatar space due to Angel's tendencies to run close (meaning you can apply max dps), coupled with non-debilitating target painter EW.
SoE LPs conversion have stayed solid for years (even after the addition of Apanake and Lanngisi).

One issue though, it's magnet for gankers and griefers (aggro bait). Keep your eyes peeled for probes within 6AU of your mission location.
Always activate your defenses after jumping gates. As a general guideline, do not bling your mods that its more than 2x your ships hull cost.

SOE Lanngisi - 0.5 sec level IV mission hub with no adjoining losec. With good skills a single burner mission pays enough LP to buy a sister's core probe launcher for 30 mill profit just on the LP.

Be warned it is 2 jumps from Hek and the crazy Hek 'nado gangs so fly a blinged pirate BS at your own risk.