If you get a chance, try and pick up and hold the guns before you buy them. I've met a fair few people who wanted an L85, but were put off by the weight after trying mine.
Own all 3 of the ICS SA80 series, have toyed around with a FAMAS. All are pretty solid.
I'll echo all of the above about the ICS SA80s. Tough and reliable, but the hop-up design leads a lot to be desired. Work best on 0.25g rounds.
My Carbine has taken a real battering over 3 years. 200K rounds (possibly more), no spares, only opened up once, after it fell in a swamp. Clocked at 310 FPS. It's only 3 inches shorter than that standard L85, so you won't save much space. Back heavy. Fine in CQB.
If you like bolting crap onto guns, the L85 can have the DD-rail handguard on the front. Like the carbine it's back heavy, but not as much. Fine in CQB
I wouldn't bother with the LSW unless you're desperate. Pretty balanced over the pistol grip, meaning the extra weight isn't really noticeable. Barely 1/2 an inch shorter than a full sized M16. Not useful if you're intending to go to a CQB site. Before it broke, I'd put upwards of 450K rounds through it (it got run over by a tw*t on a moped).
As for the FAMAS - pretty light (compared to the SA80 series anyway). They seem reliable, my friend's only broke when he did something stupid with it. Worked flawlessly, and despite being plastic, it was rock solid.
I'd say it's up to which you personally prefer, and what your budget it, but remember the L85 is about 11lbs without optics.
