I like the agglomerate corks. There are a number of brands. Make sure you buy #9 corks and I only use 1 3/4" ones. A lot depends on how long you plan on keeping the wine, but these are what I use.
Ditto the above, #9 x 1 3/4 agglomerated. Just picked up 200 of them this morning on my way to work. Ready for corking once I rinse and sanitize some bottles.
Either whats said above or the Bi-disc corks which are a step better. Both should work with a hand corker. Do not try and use synthetic with a hand corker and even a Portuguese floor corker will have a hard time with some synthetic corks.
#8s are normally used for wines to be stored less than 4 or 5 years, #9s are normally for 4-5 years or longer. But nothing says you can't use 9s for short term but I would not recomend 8s for long term. BTW 8s are easer to put in than 9s but the price is the same so the choice is yours. Does this help any?
I kind of disagree with that statement. There are many different kinds of corks out there, many of them are really only good for 2 or less years including #8. Only a few out there are rated for 4-5 years opr longer...
I use the #9 X 1 3/4" bi-disc that Wade is talking about. For splits that I'm going to test along the way, I use #9 X 1 1/2" perfect agglomerate. I use the Italian floor corker.