In all honesty i think that Gear 2nd is my favorite….but i like gear 3rd too....but sadly they both have potential weaknesses
see gear 2nd sux just because it take up an extreme amount of nutrients from the body and it is as that pigeon guy said...it's like "speed" more like doping to put it exactly. Morever, if luffy uses it for too long as we already know he becomes uterly useless.
gear 3rd however sux even more.... even though i see a great potential in gear 3rd. Gear 3rd has two major weaknessses from what i gathered
- slows down your speed due to the increased size in the body
- once used up yah shrink to a size of a kid and become as weak as one
Gear 4th...this my "theoritcial gear".. you can read about it if you want.....
it's a combo of gear 3rd and gear 2nd....in the gear (remember this is a theory!). It's actually more of gear 3rd than 2nd.....but you'll see what i mean. Anyways in this gear luffy expands not just one part of his body....by blowing into his finger he expands everything!!! Thus making him become a living giant, but in order to move such a mass he will have to use gear 2nd at the same time in order to provide movement for his body.
Well anyways that's my crazy theory.... and onto the main topic....
yes gear 2nd has been my favorite and always will be favorite. ^_^