I have both, and they are awesome watches. It boils down to lifestyle. If you are the sporty type that wants a durable watch with some fitbit features (step and distance counters, nothing fancy), then the GBD is a great choice. If you want a classic style all-around beater without the smart-watchy stuff, then go for the 5610. Both are durable, reliable, water resistant-well, both are G-Shocks. Where the GBD blows the 5610 out of the water is the screen and the numeral size:

(a side by side comparison)

Our "hobby" is cyclic in nature. We grow enamored of a piece, we buy it , we wear it, we get bored with it, we sell it or gift it. I have not set a definite amount of time, but if I have a watch that I have not worn for a significant amount of time, I gift* it to relatives or friends, because I don't want to go into the hassle of selling it. I usually gift them in a spur-of-the-moment fashion, because I know that I will try to find excuses not to give it, and then it will keep collecting dust in my box.

One of the duties of us enlightened folk is to educate our horologically challenged brethren. That's how I guided my sister from the veritable abyss of wrist junk that are called "modern women's watches" to a very respectable 8-watch collection, most of them previously owned by me. Now I am working on my brother in law, which is more of a challenge, since he has abominable taste.

*= Not the expensive ones, I am not an idiot!

Welcome!

Let's face it, diver watches are not for divers...anymore (and Girl Scout cookies are not made from real Girl Scouts, I know). But putting Rolex aside, there is (and will always be) a market for them for the obvious benefits: built like tanks, water resistant, can wear them practically in any occasion, they are the consummate everyday watch. There are plenty of professions where a diver checks all the boxes, usually manual labor-intensive ones. In  my own (doctor), I wear them because 1. I need to tell the time, 2. I need something that is water (and -ahem- "bodily fluid") resistant and can be disinfected easily.  So for me, it is a stainless steel (case and bracelet), saphire glass automatic with 50m WR (at least) by default. I assume there are professionals in other fields that have the same criteria for their day-to-day timepiece. It does not have to be break-the-bank expensive, I use $100-150 homages (Pagani, Steeldive, Heimdallr) exactly for this reason. 

And yes, they look cool.

Edit: Another reason I forgot to mention is legibility. I am no spring chicken, and I want to tell the time without having to look for my glasses all the time (pun intended). Another box checked for the diver.

I started double wristing a couple of months ago,  after a major change in my daily habits (started exercising & working out), so I started wearing a smartwatch as a fitness tracker. I am too much of a watch geek to forgo the assurance of a stainless steel, water resistant mechanical watch that does not require charging every 5-10 days, so my left wrist is reserved for "classic" watches. On the other hand (pun intended), I thought that I would look  weird rocking 2 same technology pieces, so I ended with a mechanical/solar piece on the left wrist and my smartband on the right. So far, it works for me , to the extend that I feel naked without both wrists occupied (yes, I need help...)

P.S. Besides, a smartband/fitbit style piece is discreet enough for those feeling awkward.

Only 5? It is impossible!

No, no matter how hard I tried...I have a garishly huge Fossil that was gifted to me, so I cannot sell it or gift it. My only hope is that someone steals it from me but even thieves have better taste...