I hesitate to mess with the bushy prime anymore than it has already been messed with, wait to see what the devs do with Mguns and LRM-5s first. I also agree the Madcat Prime is sacrosanct.
Time for my Atlas!
Atlas BThis Variant Sucks A subpar Hgauss boat on an Assault! Woot. The Atlas gets knocked around too much to depend on this one shot poorly ranged weapon for its damage, 1 heatsink for the PPCs is bleh, Eoptics is pointless when your max range is 700m. LRM10s are crappy when you have to get within 400m for the Hgauss to really be effective. No further backup weapons makes me sad panda. Let the Fafnir stop around with Hgauss, the Atlas has more important things todo.
My SuggestionAtlas B 'Dux'
Gauss Rifle
x2 MRM20
x3 ERMBL
ERLBL
NARC Beacon
Mgun
BAP,C3,AECM, 3 (DHS)* 2 tons free
My ArgumentThis is what an Atlas should look like boys. A command mech meant to march to the front line and provide as much support for his team and pain for his enemies as possible. It carries an MRM 20 in each side torso, while a Narc launcher is carried in its right torso along with a BAP system and a C3 computer housed in its left torso. On its left arm a Gauss rifle is gripped near its left fist while an Mgun is mounted below. On its right arm a pod of triple ERMBLs are mounted near the right fist while an ERLBL is mounted under it with 3 (Double*)Heatsinks mounted around them to tame the heat. All of these with an AECM unit mounted deep in the CT and two tons of cased ammo to boot.
The heatsinks deal with the heat well so long as the ERLBL is not constantly fired in conjunction with the MRM20s and the ERMBL give a moderate heat, good damage punch at close range whilst Gauss can reach out and touch someone cowering behind the lines. All of this with an Mgun prepared to spray and finish any BA which survives its lasers and MRMS. The NARC and C3 means you should be at the front lines dictating the battle to your support units and the two tons of ammo gives you further versatility in choosing your role. Now go stand tall on the front lines.
*Note* I was easily able to build this with 3 double heatsinks which came default on the 3062 Atlas, in fact most all of the IS mechs were coming with DHS at this time and when I looked at Sarna it said "The benefits of doubled heat dissipation capacity usually outweigh the drawbacks and by 3058 almost every 'Mech model was equipped or retrofitted with double heat sinks." The clan versions were of course smaller but the IS had them too. Why are we stuck with crappy old single heatsinks like its 2950 on the IS side? Why not use double on the bigger mechs? :/
Thanatos Prime
This Variant SucksOk, ok, I love CBT prime variants and I want most all of them to stay. But dude, this variant... so, so bad

Sure you can stay in combat forever, but its going to take forever to do any damage, and the heat will start to become a problem while on the move, which is what you should be doing with the Thanny. When I look at the Thanatos I see bigass tough guy brawler mech, not halfass laser boat with an MRM tacked on. Come on guys, even the Bushwacker gets an LBX20...
My Suggestion LBX20
MRM20
x2 MPL
GECM, JJs
My ArgumentThis is strict tonnage rules but you have to stuff the the LBX20 due to lack of crits into the Right arm and torso, I want an LBX20 on this mech, the bushy B can exist with a bit of hand waving so an LBX Than should definitely exist. This build makes sense for this mech and it was basically what used to be on this mech before .3 and it only sucked because the LBX20 sucked, now that LBX20 is good the LBX gets dropped and surprise surprise, worthless Thanatos.