The Battlesuit Hero

    One of the classic hero types since the Silver Age of Comics is the battlesuit hero.  Unlike most hero types, who are either non-powered that rely on skill and use mostly "mundane" technology (such as Batman and Hawkeye) or have innate powers (Superman, Spider-Man), the battlesuit hero relies almost entirely on a suit of powered armor, typically with built-in weaponry.  The most iconic of the battlesuit heroes is, of course, Tony Stark/Iron Man; there are others, of course, owned by Marvel, DC, Image, and smaller companies.
    There are four basic methods to produce a battlesuit hero in GURPS: Signature Gear, a set of Advantages with various Gadget modifiers, as an Ally, and as an Alternate Form.  I'll discuss each of the four methods.

Signature Gear
    The Signature Gear method is the simplest of the four methods used to build such a character: build the battlesuit as a piece of gear, determine its price tag, if necessary adjust for being a higher TL item, and purchase the whole thing with the Signature Gear Advantage.
    On the one hand, this method may be preferred due to its simplicity.  However, this method requires that the battlesuit has a price tag.  If using one of the suits in GURPS Ultra-Tech or adapting from a design built using GURPS Classic: Vehicles or GURPS Classic: Mecha, the price in G$ is relatively easy to obtain.  On the other hand, it is not always appropriate for one-of-a-kind suits (like most of Iron Man's suits).
    As an example, let's take a TL10 Commando Battlesuit (Ultra-Tech, p. 183, 186).  At TL10, it costs $80,000; in a typical modern-day superhero setting this could appear at TL8 as a prototype.  Due to being two tech levels above the setting, the price is quadrupled, for $320,000.  At TL8, each point in Signature Gear nets a value of $10,000; this means the suit requires "Signature Gear (Commando Battlesuit) [32]".  In addition, Signature Gear means the suit has some form of "plot protection", enabling it to get replaced if stolen or destroyed.
    This cheap price can be useful in a fairly low-powered (250 points) setting.  I don't recommend using this method for 500+ point campaigns.

As an Ally
    As explained in The Captain's Boat (Pyramid #3/71, pp. 32-33), a vehicle - and here I count battlesuits, especially those supported by an integral AI - may be purchased as a base 5-point Ally, without adjusting for Frequency of Appearance.  More customized battlesuits can be built with a higher base Ally cost.
    For a battlesuit hero on a strict point budget (say, 150 points), this can be considered the most cost-effective method.  On the other hand, it is often considered a "point crock," as it makes owning or operating a battlesuit too affordable for some games; a character can get a major benefit for only a handful of points.

Advantages with Gadget Limitations
    The method taken by GURPS Supers is to treat the battlesuit as a set of Advantages, each possessing the "Gadget/Can Be Stolen (Must Be Forcibly Removed) (-10%)" limitation, often accompanied with a few Temporary Disadvantages (Electrical, Maintenance, and Unhealing are common).
    From the point of view of point costs, this is one of the fairer methods, especially when compared to various brick and blaster builds.  However, it can be a pain during character generation, especially when trying to add the limitations for every advantage in the suit.  To offset this, I recommend using a variation of the "Meta-Enhancement" rule from GURPS Power-Ups 4: Enhancements, treating a set of limitations as a single "Meta-Limitation", writing just the Meta-Limitation name (e.g. "Battlesuit, -40%") on each advantage, and a note on the sheet detailing which limitations are used.
    This method often has other questions asked during character generation: "If a part of the suit has is supposed to be Gadget/Breakable, what SM is the relevant body part?" "Do I need Switchable and/or Takes Extra Time on everything in order to don the armor?"  The GM must be ready to answer these questions.  A player may get frustrated with this method and decide to choose a different type of character, one not quite so complicated.

    (Sadly, I'm currently lacking an example build, as the build I was going to use as an example has been replaced by an Alternate Form build.)

Alternate Form
    My current preferred method: build the suit as if it was a racial package and calculate it as an Alternate Form.  This lets you define the Advantages without needing to specify a gaggle of Gadget and Temporary Disadvantages.  Such traits are defined as full-fledged Disadvantages in the racial package.
    After determining the point cost of the "racial" package for the battlesuit, the Alternate Form advantage on the primary character sheet is calculated: 15 + (90% of the racial package cost).  At this point, add the Gadget/Can Be Stolen (Forcibly Removed) limitation directly to the Alternate Form trait.  If it takes longer than 10 seconds to don the armor, you can use the Takes Extra Time limitation (p. B115) to extend the time.
    On the plus side, if the character owns multiple suits he can change into, each additional suit of equal or lower point value is worth only 15 points.
    Here is one build for a battlesuit with wings:

634 points
Attribute Adjustments: ST +24 [240].
Advantages: Clinging [20]; Combat Reflexes (Accessibility: Only On Opponents Whose Style Is Programmed In, -20%) [12]; Damage Resistance 12 (Partial: Torso and Groin Only, -5%; Hardened 1, +20%) [69]; Damage Resistance 30 [150]; Electrolaser: Burning Attack 1d (Link, +10%) [6] plus Affliction 4 (HT-3; Link, +10%) [44]; Enhanced Move (Air) 1.5 [30]; Flight (Winged, -25%) [30]; Infravision [9]; Ladar (Targeting Only, -40%) [12]; Protected Vision [5]; Sealed [15]; Telecommunications (Radio) [10].
Perks: Accessory: Personal Computer [1].
Disadvantages: Electrical [-20].

On the main character sheet, I list the following:
Advantages: Alternate Form (Battlesuit) (Gadget/Can Be Stolen: Forcibly Removed, -10%) [585]

    (Yes, this is my build for the Beetle for my Marvel Reboot project.  I would have used Iron Man as an example, but I'm still working on his suits' racial packages.)

    Each method has their own strengths and weaknesses.  Personally, I prefer the Alternate Form method for battlesuit characters, as it combines a point cost comparable with other superhero abilities with a simplistic method.