depends what you want.

The GSR is better because:
Higher compression =more power with less boost
Stronger Ringlands
better geared transmission
8200rpm Redline
VTEC

The problem with the LS engines is that they have a long geared transmission and a low redline. The heads dont flow much past 350whp, ive seen maybe 2 or 3 guys locally make over 400whp with stock heads. a stock GSR head can handle 600whp no problem.

The LS wont make as much power all things being equal.

But, the LS is cheaper, has a longer stroke so generally more TQ compared to the GSR.

if your goals are 250whp an under, its fine