I actually prefer the strogg (Q2) over quake one. Both were amazing games though. Quake 2, classic doom, and starcraft are probably my top 3 classics, in no order.
One thing I really liked in the original quake over Q2 was the thunder bolt, and the creativity of some of the bosses, I remember some were more like puzzles where instead of constantly unloading rockets, there was actually a trick to killing them. whether it be a telefrag, or electric shocks to the lava monster, quake one had some real interesting bosses. Similar to the final boss in doom 2.
super nail gun was also fun
oh, and the rail gun guys in Q2 were called gladiators. they are actually quite easy to defeat at close range, the trick is to take the double shotgun, and stay just outside of their swinging range with the claw. they wont try to rail you, and will instead chase with the melee attack. however, if they do have a shot on you, they usually hit and it hurts.
and finally, I would like to give mention to one of my favorite tactical games of all time, one of the most under appreciated, under supported games from id software, (and splashdamage) the great enemy territory quake wars.