Currently have maxed 5* greens:
Gregorion
MN
3/70:
Evelyn
Kingston
Lianna (/w costume)
Margaret
4* maxed:
Caedmon
Gad
LJ
It should be clear that Margaret is not in consideration. Was torn between Evelyn and Kingston, but I’m wondering if Lianna’s costume bonus puts her over the edge?
Evelyn is great, but her job is to make Kingston or Lianna hit harder, so one of them should definitely get the nod. Kingston would be a no brainer over normal Lianna, but her costume looks pretty ridiculous. Would they be going on your D team? If so, I’d probably go for whoever has less competition for emblems. Kingston has a stronger case for fighter emblems than Lianna does for ranger emblems, but that really depends on the context of your roster. I didn’t luck into Lianna’s costume last month, so I haven’t thought that deeply about it yet, but it really does look pretty good and should probably make her climb the ranger rankings a bit, even if she isn’t the top candidate overall.
Likely that none will be on defense or get many emblems. Really thinking just about stacking for wars/raids and titans.
Costume bonus makes default Lianna the hardest hitting sniper in the game. Her attack stat is a bit higher than Kingstons when her costume is maxed (both with or without equipping the costume), and her snipe (which was already the strongest) becomes even more devastating.
Lianna (costume not maxed)
729, 
718, 
1248
Lianna (costume maxed, not equipped)
765, 753, 1372
That said, you don’t get the benefit of the attack down from Kingston – which frankly seems very useful for fighting titans and surviving their strikes. Ditto tough bosses.
In that case I think it mostly comes down to if you value the mana or attack debuff more. I think the attack down is probably a bit better, on the balance. Both are really strong choices though and it might be down to who else you have on your roster.
Evelyn if you are facing 12* or hugher titans. If not, she can stay at 70 till then.
I went with Kingston over Lianna and I have been happy with it. I use Evelyn + Greg + Kingston and its usually good enough for 2 kills (be sure to give Greg the mana troops).
It’s a very hard call with her costume. However, because I use Mono, Kingstons mana bump makes a real difference. You wont see it until you get some mana troops up, but its noticeable.
I’m making a number of inferences here, but based on your comment that none will compete for emblems, I’m assuming you have a deep and talented bench, are likely in a top-ish alliance, and fight high level titans. For those (possibly incorrect reasons), I’m leaning towards Evelyn.
Evelyn + Greg is probably enough to get many kills, and I worry that 3.70 Evelyn won’t live long enough against the stout competition you face.
If I’m wrong and 3.70 Evelyn lives long enough, then great! I’d go with Lianna in that case, partially because the amount of time to max her plus her costume gives you more time to accumulate the necessary mats for Kingston. That is, if you’re maxing both Lianna and Kingston, this order may give both slightly sooner than Kingston then Lianna. I know it’s a small thing, but since it’s close I’m comfortable making the decision on a fairly arbitrary criteria.
My alliance is definitely below the top tier, highest titans we fight are 10*. It’s more casual and I’m one of the higher end players on it.
I’m not loaded across the board, it just so happens that there’s a few classes that I am very deep in with great heroes, and Ranger/Fighter are among them.
For titans, Evelyn lives long enough at 3/70 for up to at least 12s. I didn’t use her for raiding until I got her maxed. I used Buddy instead.
I run a 3/70 Eve on my Mono green B team in war and she can hold her own. Obviously more fragile but I’m fighting 4300-4500 teams and I’m 4/5 with the B team in the last 5 wars vs blue tanks.
Kingston first - he’s more flexible. If your hit can’t kill an enemy, you can neuter him w Kingston. If Lianna doesn’t finish an enemy, you get the full hit back, and Eve needs two or three snipers to follow her to be most
Effective.
King - Eve -
Lianna would be my progress, and I run all three on my mono A team w North.
Evelyn @ 3/70
I would choose costumed Lianna above Kingston if you do not have lv29 mana troop to drop mana charge by 1 tile (lv17 mana troop works for costumed Lianna).
If you have lv29 mana troop, Kingston is possibly better with elemental link but most importantly he reduces the damage done by 3 targets.
Okay, I over-estimated the titan and war situations you were facing. Based on the way you talked about emblems I also assumed you already had 2-3 top shelf options in all classes; it sounds like you are saying you’re just unusually talented in the relevant classes because of RNG, etc.
Based on this new information, I will now update my opinion: I now agree with those who say Evelyn 3.70 will be serviceable for now and you should go a different direction. I look at both Lianna and Kingston as very compelling options and would make the final decision based on what else you have.
Ultimately, I’d choose whoever does something you can’t otherwise do. Factors like: if you already have a powerful complement of attack debuffers (say, Scarlett, Richard, and Skittleskull), then that’s a negative for Kingston. And, as AirHawk points out, your mana troop is relevant - if Lianna’s costume shaves a tile, that’s a benefit.