I feel a certain need to give you a brief edu-ma-cation. Forgive me if i come off as a tad condescending, i do that sometimes. My purpose is only to inform, not to talk down to you.
To a certain extent, all gundams will look alike. Notice that even the G Gundam ones i showed you all share similar characteristics. That's because they are all
GUNDAMS. It's the same way with cars. Cars are all different... but all Hondas share similar characteristics as do Chevys, Fords, etc. Every Gundam ever designed is based in some way off the first Gundam, from the original series Mobile Suit Gundam.
The grand-daddy of them all, the RX-78-2 Gundam.
http://gundam.wikia.com/wiki/RX-78-2_GundamThis one started it all. No matter how obscure the design, every Gundam will resemble this machine in some way. That's just the way it is. Deviate too much and fans no longer recognize it as a Gundam.
It's funny you mention Exia as the 00 designs ticked off a lot of fans at first.
http://gundam.wikia.com/wiki/ExiaLooking at the Exia, you'll notice some differences from the standard Gundam design. The V-Fin on the forehead is a little different, there is no side-skirt armor at all, but the biggest change comes when you turn the machine around and look at it's back and notice a giant dome sticking out of it. This, the GN Drive, is the Gundam's propulsion unit. In the 00 universe, the Gundams do not use traditional thrusters or engines for movement. Instead they move by use of special particles, or as some of us like to call it, magic.
This is unique to the 00 universe, as are a lot of other mobile suit designs.
Over Flag
http://gundam.wikia.com/wiki/SVMS-01O_Over_FlagTieren
http://gundam.wikia.com/wiki/MSJ-06II-A ... round_TypeArche Gundam
http://gundam.wikia.com/wiki/Arche_GundamThat's just a sample mind you. For another extreme mobile suit design, we turn to a different universe for the Turn A Gundam.
http://gundam.wikia.com/wiki/WD-M01_Turn_A_GundamArguably the most unique and unrecognizable of Gundam designs, it shares very little in common with it's forerunners. The V-Fin has been moved to the chin for example to form an almost comical mustache. The cockpit, no pun intended, is located on the crotch of the machine. Furthermore there is just the overall design. Paint this a different color scheme and i doubt anyone would recognize it for a Gundam.
Not everything in Gundam is about Gundams. Many of the more famous and popular designs are not Gundams at all, but rather "bad guy" suits. There's the classic Zaku, which lead to countless more Zeon type suits.
Here, we have a basic Zaku II from the UC Gundam universe.
http://gundam.wikia.com/wiki/Zaku_IIThis design spawned countless variations and mobile suits for the UC Universe, and while many were considered cannon fodder, there are fan favorites such as the Sinanju.
http://gundam.wikia.com/wiki/MSN-06S_SinanjuThe basic Zakus, Goufs and even Doms got some love in Gundam SEED Destiny. Getting a major overhaul, these suits were no longer just cannon fodder.
UC Zaku II
http://gundam.wikia.com/wiki/Zaku_IISEED Destiny ZAKU Warrior
http://gundam.wikia.com/wiki/ZGMF-1000_ZAKU_WarriorUC Gouf
http://gundam.wikia.com/wiki/MS-07_GoufSEED Destiny GOUF Ignited
http://gundam.wikia.com/wiki/ZGMF-X2000_GOUF_IgnitedUC Dom
http://gundam.wikia.com/wiki/MS-09_DomSEED Destiny DOM Trooper
http://gundam.wikia.com/wiki/ZGMF-XX09T_DOM_TrooperAs you can see, the Gundam meta-universe is about far more than Gundams. Yes, all Gundams look alike to some extent, but the same can be said of all Lamborghinis. It's not necessarily a bad thing. I suggest spending some time browsing the Gundam wiki (
http://gundam.wikia.com) or
http://www.mahq.net or even the master grade and high grade sections of an online store such as
http://www.gundamstoreandmore.com. You never know what new mobile suit designs you'll discover.
On a final note, I am going to link you to my favorite mobile suit, one that isn't even a Gundam. The picture below is a fan-custom. There is no Master Grade yet, but i am very hopeful.
http://gundam.wikia.com/wiki/OZ-00MS_Tallgeese