A couple of weeks back, Sarna.net had a column of their five favorite 'Mechs from the 3050 TRO. (http://www.sarna.net/news/your-five-favorite-is-mechs-from-3050/) This is the first one that has Clan 'Mechs in and the major upgrades are in place.
I'm going to stick with just the brand new designs that first appear in 3050, because I would be repeating myself, because most of my favorites got upgrades that I liked. So, three clan designs and two Inner Sphere ones for this post. (Images are from Sarna.net, and belong to FASA/FanPro/CGL. I have no claim to them as my own)
Mad Dog (Inner Sphere: Vulture or Hagetaka)
Mad Cat (Timber Wolf)
There's been only a few iconic 'Mechs in the last 30 years, and one of those few has to be the Timber Wolf. It looks like a weapon of war, from its cockpit, pod arms and massive missile racks. It's fast for its size, with enough firepower to stomp on anything that gets in its way. My favorite variants are the Prime (Paired LRM20s, ER large lasers ER medium lasers, and machine guns with a single medium pulse laser) and the Pryde (Paired LRM20s, ER large lasers ER medium lasers, a single ER small laser, and jump jets)
In my book, one of the scariest Clan Mechs is the Warhawk. When I was playing in a gaming club, I'd call it a "Massacre", because that's that it would do to any target in its sights. With almost every version carrying a targeting computer, this monster could hit and inflict serious damage at ranges Inner Sphere pilots could only dream about. I like the Prime (4 ERPPCs, LRM10), the C (2 ERPPCs, 2 large pulse lasers, flamer) and H (LRM10, 2 large pulse lasers, 2 large heavy lasers).
"Speak loudly and carry a bigger stick (and use it too!)" sort of describes the Axman. The Hatchetman's big brother, this 'Mech is best in urban environments where long range weapons are limited. With a AC/20-- ax combination, letting this monster get close is suicide. I used this design in my Battlecorps story, The Promise, and wrote a battle between an Axman and a No-Datchi, in which the duel descended into a brutal ax versus sword fight.
Another "big brother," the Marauder II is a is a monster that can jump and take a lot of punishment as well as deal it out. I like the 4K variant (2 heavy PPCs, two ER small lasers, Gauss rifle) and the 4S (2 ERPPCs, 2 ER medium lasers, Heavy Gauss rifle).
Those are my choices. Anyone have one of their own?