Missions & Complexes

The domi is a great "cost effective" boat. however, "cost effective" is so plebeian.

I guess my answer somewhat depends on where you decide to run missions. the 3 highsec agents are in caldari/amarr/minmatar space, with the two in amarr/minmatar space being preferable. However for both I would suggest a Machariel. and given they are so cheap you might even want two, one AC, and one arty fit. Swapping fits is pretty easy, swapping ships is even easier. beyond that I like the paladin, although don't think it would be as useful in minmatar space, I would probably just fly a mach out there. might want a vargur, but I feel like the mach will just do better in most cases.

if you really want a drone boat, the rattlesnake can do some cool things, but I find the combination of missiles and drones to just be annoying.

SOE are the easy mode ISK makers.

Some drone boats:

Sentry Domi - easy semi-afk generic mission workhorse. Does a great job with just a T2 fit.
Gila - never tried one
Ishtar - handles level IVs well with advantage it can also rat those annoying anoms with gates banning battleships
Rattlesnake - on paper max DPS (up around 1800 with good skills) but in practice hard to fit and fly. Probably the best blitzer if you have the skills and are prepared for the workload.

basically cost is not even a factor, just want to try something new and make some isk or at least a chance at a cool drop, or some neat hard to come by faction lp stuff.

The Dominix is great when it comes to T2-fit T2 sentry drones with MJD. The Rattlesnake will lose some potential DPS advantage due to limited highslots for missile launchers and Drone Link Augmenters (you'll want at least 100km drone control range if you're using MJD for range).

The Rattlesnake will get decently high DPS with a Gecko and torpedoes, but that ship will only be effective at very close range. It will be an exciting ride, until you have each mission figured out. After that you'll find yourself grumbling about the need to MWD into range, or the need to spend even more ISK on Javelin torpedoes.

The Ishtar can't use MJD, but the Eos can. You'll get better DPS out of a Dominix or Rattlesnake, but slower align/warp speed.

A better all-round mission boat is the Machariel. It's fast, agile, has a warp speed bonus so you waste less time moving around, and packs the best damage application of any mission-boat you will fly. It's not just about DPS, it's also about hitting enemy ships and doing the most possible damage to those ships per salvo.

I'm a very lazy mission-runner, so I have a mix of ships to use depending on how bored or distracted I'm feeling: CNR, Dominix, Rattlesnake.

YMMV.

In all cases, mission-running is slightly less boring than watching spiders building webs in my architraves.

"I'm bored so I'm going to go run missions!"

Wrong plan mate.

TP sounds like a good idea on paper but in fact you just wait for it's cycle time far too much.

Third omni can be scripted to provide on demand stats and it's always active (though I wish it's cycle time was lower)

In regards to the Rattlesnake, yes you can get almost 1800 dps; but that dps is almost evenly split between drones and missiles. So the actual damage application is slower in my opinion than a Macherial or Paladin. For best isk/hr, you can't go far wrong with the Macherial, Paladin, or Kronos.

In some missions I like to use a blaster vindicator. It takes some time to close up, but when you get there, everything just melt.

Machariel is the best, if your skills are maxed out for it. With low skills Gila is the best.

With a Rattler its not such a big issue as in missile only ships. You can target the BS with missiles and small targets with sentries and then each time a BS is down near structure move the missiles to a new BS and finish the current one off with your sentries.

You end up with a high workload but it lets you actually apply all that DPS without really wasting any.