The G-5600 is solar powered. Maybe you mean the DW-5600?
I've got a GW-9110 (atomic solar Gulfman) and DW-5000 (which has the same design as the 5600-series, but with a screwback) and although I like big watches, I think I would pick the 5600-series. Or better: a DW-5000SL for it's screwback. Easy to find on the bay in Europe. The strap of that watch is softer than the one on the Gulfman.
It depends upon the look you're going for. The DW-5600 and G-9100 are two very different looking watches. The 5600 is square and lower profile, while the 9100 is round and rather thick. Functionality wise, they're pretty similar.
I have the GW-9100 and I really like it. The band is not as comfortable as on the DW-5600, but that's easily remedied.
BUT... rather than starting all of these one sentence threads with basically the same kind of very generalized question with so little information to go on (you're not specific in the least), why don't you just spend some time reading the forum and observing the Casio G-Shock watch designs? Asking for opinions on questions like "which G-Shock is better", "what G-Shock should I get first" or "what is the most beautiful G-Shock" is not going to help you at all. Your choice has to be based on your personal preferences. And if you've no idea what you're looking for, we certainly won't be able to help you. Write down a list of what features you're looking for and start narrowing it down from there. Also, check out the FAQ.
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