Not to rain on anyone else's parade, but the Atlas just... doesn't excite me. Never has. It's just a giant honking block of armor with 3/5 speed and half the firepower of an Archer. Or roughly the same firepower as the Whitworth. WOOOOOW. Sure, it's got a LOT of armor, but unless one of the two players is defending a chokepoint, none of those 9" range guns on the 7-D matter when it can just be whittled down from range. Okay sure, it's got a bulbous skull head? Yaaaaaaay, skulls are totally overdone in miniature wargames.
And any variation on it that I would want, has already been designed. Cheap and cheerful support 'Mech? AS7-RS. Expensive fire support? AS7-K. Less expensive version of the 7-K? Atlas II and Titan II. Super-heavy firepower on a pillbox? Annihilator series. Double boom-sticks? Fafnir or Pillager series. Triple boom sticks? Thunder Hawk for total wretched excess. ACTUAL useful fire-support at 100t? Imp series. Just as anemic as the Atlas but with waaaay more character? King Crab series, or the Marauder II.
Plus there's the Berserker as a case study in how not to ever design a melee 'Mech.
I kept trying to get excited about the Atlas, but it just doesn't speak to me, at all, in the slightest. I know it's "iconic", but I just don't see how it's anywhere as good as the other iconic 'Mechs in the game, or even just in the 3025 tech readout. Without its quirks (and plenty of people don't use quirks) it's just utterly mediocre, which is not what you want in your expensive assault 'Mechs. WITH the quirks, it's... slightly better than OK? I guess it'll keep your commander alive and useful except for the occasional lucky head shot.
I guess I just don't use the 100-ton 'Mechs, not when there's so many more useful 'Mechs at lower tonnages. But if I ever had to field a 100-tonner, I'd reach straight for the Clan second-line options: Jupiter 1 and Bane 3. Pure delicious oozing cheese in a fire support package. Practically a "win" button for each.
And I admit I own an Archangel, but it came as part of a set, I swear.
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edit: I double-checked the BV, and I can field two whitworths for one 7-D atlas, which is a trade I would take every day, and twice on Sundays. Even in alpha strike, which is much kinder to the 7-D atlas, two Whitworths are still a decent trade (and the PV still works for a 2:1 swap).