Yeah like Max said since i joined i mainly used DH as it was just a personal favourite of mine, however i find his range is limited and recquires you to be a bit closer than normal. But that's just me, Lanny is an ok trans i think it's over-rated. Ice-Kong can be decent, Lady valor is just awful but pretty looking.
Musz - NEVER get, it's fall down recovery is awful and attack speed isn't excatly great either.
Steel Golem - " " ^
Bee-Byte - can be ok to use if you fancy being different
Searget Sector - Awful
Lion Mecha - With his combo you can spam range his fire breath just like Mandragore.
Mandragore - Giga trans totally worth the money, it's combo. Just makes it a personal favourite.
Double Blade - Never used.
White Ninja - Never used.
Lanny - All round trans, can mainly be used for pushing well, and is fast paced.
RedTeam (Hallo Trans) - Fast, but don't know what to say.
OverRunner - Short, Stumpy, Chode. Mainly used in PvP, BvB.
Frosty - Never used.
SuperKhanz is also a common trans i see about, similar to lanny but with it's own qualities
Ice-Kong - Has a cool animation when he attacks, can combo well.
Jura - OP, over-rated but good to own.
Mega-Bot - Never used.
Digi-Dragon - When he jumps and attacks he does a fire breath can be good for spamming from a distance which can be used all game modes
Dark-Knight - Sector mainly
Cba to go into detail about more... but Mandragore ftw.