looks like rock band is the choice. guitar hero can 

Guitar Hero Live:
No backward compatible DLC, disc content, or instruments.
Live band reaction? Making new DLC seriously more difficult to produce new songs not to mention the repeatitive nature of the audience.
GH TV sounds like licensing issues run amuck.
Only guitar based play with no band play? Good by drunken kareoke.
New 6 button guitar looks interesting but gameplay looks kinda bland and colorless.
Rock Band 4:
95% of over 2000 DLC to transfer over to new RB4.
Back to origins with all RB plastic instruments back compatible. (Not sure on keys, pro, or harmonies.)
Same old style of background video of customized created bandmates.
Haven't heard of online play plans yet but would assume similar to RB3.
Not alot of new. Basically same as most music games with some graphic enhancements.