I suppose that with the leaves you might get a bit more nitrogen, but the main consideration is whether you use a tree trimmer with a heavy truck or not. In my case I would wait until the ground is very solid so as not to leave deep ruts.

not a worry
both can be taken down from the street

I would think that if you're using some for compost or mulch, leaves shouldn't make a difference either way. If you're using it for firewood, leaves just create smoke, don't they?

Are the poor trees dying and that's why they need to be removed?

Green leaves mixed in wood chips provide some Nitrogen so they can be a good thing, althouhg often that means the wood chips are digested faster because the bacteria have a good food source readily available. Just when to take down trees is always a dilema, but I find the best time to be when the crew can get there.
Hopefully you are going to use commercial tree removers and not do this yourself.

It's a lot easier felling and bucking a tree with no leaves.

I'd say its not worth the risk of waiting. Prefer to take it down sooner rather than later if its threatening to fall.

I would take it down before the leaves come in.

I would think that removing the trees before the sap starts flowing would be best. The wood would be drier for firewood and even better, saw it into lumber for those woodworking projects. Maple should have a better use than firewood or mulch.

thanks for all the responses
I'll let you know what happens

Sure thing, the drier the better and if its a d.i.y. thing, less leaves leaves you to see what you're doing better.

Kimm, what's the matter about cutting a tree down yourself if you have whatwithall and wherewithall to get it done.
Paying, perhaps exhorbitant amounts of money just to put a chainsaw to a piece of wood seems, to me, one way to put a large amount of money in someone else's pocket instead of leaving it where it is.

If a person isn't afraid to use a chainsaw up in the tree---that's the big thing--that's the thing that scares people off--handling a chainsaw...along with other array of saws, ropes and ladder, up a platform whose footing isn't always a firm one.

Other things to consider are whether or not the chipped wood might make more nutritious mulch if the sap were allowed to rise. It's the lifeblood of the tree so possibly a great fertilizer. Might also make a faster burning firewood altho that might not be beneficial.

Also, the roots with sap might have more strength to send out suckers. Last year about this time DH took down a large aspen and I've been cutting off many shoots coming up from the roots all over my garden. Eventually the roots will die but in the meantime the lopper is my best friend. *rolleyes* Not sure if maples sucker as much but it wouldn't surprise me.

well I cut down the first one and chipped everything but the main trunk and what could be used as firewood.
It actually measured out to be 52 feet and the chippings are heating up extremely well.
took about 4 hours and all went well
except now instead of calling me darth
just call me lefty