I've owned one Mako, two monsters and various SXK007 or variants. The Mako is good, but the Seiko's are better watches. I love the Monster, but the Seiko 007 is more versatile... you can dress it up with a $15 leather strap: The Monsters were recently updated with a new movement, which makes the original version cheaper to buy... and believe me, no need for the new movement, the original has been powering watches for more than 20 years... its a great workhorse movement.Try watchrecon.com to see what is available in the used market, and also become a member of watchuseek and/or divewatchconnection forums. If you want more pictures of have questions regarding the watches, let me know.
yeah, i highly recommend G-shock, for its high reputation and excellent durability, and also so tough and classic
Seiko Monster is great, and I have one, but if I could only have one watch it would be a G-Shock. Very tough, 200m WR, backlight, countdown timer, alarms, stopwatch etc, plus solar power and radio control in many cases.