Alright, within those restrictions and based on my own experience: a triple UAC/2 Dragon 5N, any Rifleman or Jagermech (pick your flavor of compatibility for different energy/ballistic builds, a Grasshopper or Thunderbolt if you want slightly old-fashioned laservom, or a Warhammer 6R with 2x Gauss and ERMLas backup.
I'm more of a light guy. Keep in mind that "scouting" isn't something you build a 'mech for, it's something that happens largely incidentally if you're playing a fast light properly. For IS lights the main question right now is whether it can do a decent job of sustaining 6 MLas. The Wolfhound 2 does this very well as it can spare a good chunk of tonnage for extra heatsinks on top of being pretty tanky. The Osiris 4D has excellent speed, agility, weapon geometry, and can run with jumpjets without sacrificing anything, though it does also tend to run hot. Damn solid 'mech though. Those would be my two main recommendations for all-rounder lights.
Generally speaking the rest break down like this for the IS:
-Urbies: Very small mediums. Carry lots of weapons for their tonnage, move a bit slower, very tanky. Good 'mechs, but they don't play much like other lights.
-Jenners, Firestarters, Panthers, Commandos: Mostly formerly good 'mechs that were ruined by the great rescale, terrible hitboxes, and in some cases the inability to carry enough potential damage to compete these days. The premium Firestarters (Ember and Firestorm) work alright as HMG carriers.
-Javelins: Run around poking things with SRM2s. Die if anything looks at you. They're decent but really easy to do badly in if you mess up.
-Spiders: Very fun to run around with, woefully undergunned. Range from the SDR-5K's "Well at least it can carry four MGs" to the SDR-5D's "Well at least it can mount ECM" to the SDR-5V's "Well at least it can launch itself into orbit". Even if you're an experienced light jock you'll have a really hard time putting up good damage.
-Ravens: The Raven 3L used to be one of the most common lights to see, given the combination of ECM, high corner-mounted energy hardpoints, and the tonnage to carry 2x ERLLas. Also stereotypically the last 'mech alive after a stomp. They have decent torso geometry & great weapon geometry but get screwed by their giant legs, flat backs. I still love mine but would not recommend them.
-Locusts: Used to be god, some of them. Then PGI nerfed the quirk and weapon that made the 1V viable, nerfed IS SPLas for no reason, making the 1E, 3M, and PB no longer good. The rest are and always have been total garbage. They used to be dangerous backstabbing crotch-rockets with paper armor. Now they're not nearly as dangerous.
-The remaining Wolfhounds: Still good, not as good as the 2, since they either have 5E hardpoints or (for the 1A) slightly less optimal hardpoint distribution.
-The remaining Osiris variants: various shades of meh thanks to worse hardpoint counts, locations, &c.
You
can hypothetically do well in anything, but a lot of IS lights are honestly just not very good these days.
Edited by Alexander of Macedon, 18 May 2018 - 07:55 PM.