Personally, I prefer the melee Warframes like Excalibur, Ash or Rhino. As was said, their abilities are effective at clearing whole waves of guys and/or helping you stay alive.
That said, all the caster classes (except maybe Mag) synergize really well with the group, and I think they're almost necessary to do Defense Missions beyond Wave 15. I suppose they maybe fixed it by now, but I watched a Nyx literally mind control an entire wave of Infested on Wave 15. We just sat back and watched all the Ancients beat the shit out of each other while we had to literally do nothing.
So yeah, in terms of personal performance I think the Melee frames are superior. (With Excalibur being the easiest to use and the having the most straightforward, straight up damage abilities.) In terms of group performance, the Caster frames are better.
I prefer high accuracy weaponry with high skill ceiling, if that's relevant.
This has almost zero to do with Warframes and pretty much everything to do with Weapon choice. Warframes and their powers are weapon-agnostic; their powers and statistics do not synergize with your weapon choice hardly at all. Sure, Loki is useful for people who like sniping because you can pop invis and shoot without being bothered. Or using Banshee and a Sniper weapon (although it sounds like it's highly random whether or not get you the full benefit out of it.) And yes, most of the Caster Warframes (except Frost and a specific way to play Trinity) are more flimsy so you can't play as recklessly.
But generally all powers do one thing that has no bearing on shooting your gun. And weapon choices aren't restricted by Warframe.
My "high accuracy, high skill ceiling" friend prefers the Lex as his main weapon. It's basically a hand cannon that does ridiculous damage on crit, but you have to pick your shots and be methodical. Powers.....they just don't work like that. The only real "skill" in using powers is say, Excalibur's Super Jump. It requires skill to use right because the jump trajectory is so silly that you'll often misjudge where you need to jump from, making the whole exercise pointless. MOST powers don't require a great deal of aiming, timing or judgment on when to use them. Half of them are AOEs, self-guided or self buffs. There's usually your "Cheap" 25 Power ability that's meant to be spammed (Pull for Mag I think, Slash Dash for Excalibur, Shuriken for Ash.) Then you typically have 1 to 2 utility powers. (Smoke Bomb, Teleport for Ash, Radial Blind and Super Jump for Excalibur.) Then you'll have an ultimate that will take most of your power for some big, AoE damage effect. (Blade Storm for Ash, Radial Javelin for Excalibur, and typically whatever crazy AoE powers the Caster frames are packing.)
The Warframes are all very balanced, in the context of PvE where they all kickass in their own highly specific way.
The Warframe you probably don't want to play is Excalibur, as their powers are very straightforward, require little skill and truly, Slash Dash is the only power worth equipping IMO. Straight damage to all targets in a 30x5 meter radius, you just pass through bad guys AND you're invulnerable? It basically renders Radial Blind useless for anything but rezzing, because Slash Dash does damage, hits everything in a path bar nothing and can be spammed to get you out of trouble in a flash.