Well....... I have Ransuer and Legate. Both are great for missions. Same pay. I also had a Zoner Dread Zoner ID doing missions in Omicron Mu. But the ship isn't useful. So I would recommend a Corsair Legate, its a useful ship, imo, and its good for missions. I get about 12-17mill per mission in 4-5mins.
EDIT: I also heard GRN Missions are good, fighting Council in Burgundy.
Buy a Valor and go to Orkney. Those Council cruisers are almost impossible to miss, while they don't deal you great amounts of damage. If they appear with Rademptions, just strafe up-down, and you'll be alright. Gunboats are tough targets for the Valor, since she can't fire any of her 4 heavies backwards, at point blank upwards, and at point blank downwards.
Oh, and the best missions are in Fort Albi. The Valor can do even those for 5mils, if you have freindly NPCs drawing enemy's fire away from you. The repairs are usually between 200k and 2mils, but the loot is expensive, between 2.8mils and 6.2mils.
I've tried them all , almost .
Best - Legate , in Gamma or Eta (in Eta around 20-25mils/mission , in Gamma around 15-20/mission but way faster) .
Valor - not even close , unless you are satisfied with 5-10 mils/mission .
Same to Lib Dread/Carrier .
Order missions - not bad , you can make around 10 mils , maybe 15 mils / mission .
RNC - in O15 around 10-15 mils/mission , but way harder than with Legate .
uff .. forgot about OC - you can make around 10-15 , maybe 20 mils /mission , especialy in Eta , but i didn't liked the OC BS whatsoever . I was terrible bad in it no matter what i've tried .