Best NPN fet? Cheapest? What do you use?

[Mechatrommer]

AO3400 33mOhm @ 4.5Vgs, 1nF max Cgs though, few KHz PWM should be fine... the fun part is... that sot23 tiny little bastard can pass 5A like nothing so the DS said. 8 US cents in 100qty...
http://www.ebay.com.my/itm/171177440326?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

[Christopher]

I remember using a 2n7002 (which is apparantly now obsolete) to switch a relay which drew 400ma... magic smoke time!

2n7000 will be fine,  if you can handle the rds on (if your leds are low current it'll be fine)

[Cliff Matthews]

AO3400 33mOhm @ 4.5Vgs, 1nF max
..can pass 5A like nothing
..8 US cents

Wow! When I finally make my trip into SMD, a strip of those will be my first victims 

[Mechatrommer]

i just figured out from a circuit... TPCA8028 in somekind of mini soic?... darn 2mOhm Rdson, darn 50A but the datasheet i just downloaded say "not suitable for new design" must be obsoleted, must gotta have new chip with that kinda performance, gotta look for it sometime... so thats how they did it in 60A ESC...