How will this be balanced? I really wanna go with Innersphere but my buddy that loves Battletech and Mechwarrior says go clan all the way they have way better gear?
This problem is a tad more complex.
First, there are two game modes in MWLL: SolarisArena (SA) and Trial of Annihilation (ToA).
SA, a teambased Deathmatch game mode, will only by name make a distinction between the teams. Both teams have access to the full bandwidth of technology.
ToA, an objective-based game mode, will have IS technology for the Inner Sphere and Clan technology for the Clans.
A key feature of MWLL is a per-round economy - every player can only use that piece of equipment they can actually afford. As you correctly mentioned, Clan has technological advantages, therefore Clan weaponry is more expensive than IS weaponry. In addition, as Korjax pointed out already, Clan technology has its share of disadvantages as well which have been implemented as well of course.
I hope this clarifies the situation a bit.