I thought I'd post my current (current being the keyword, there will be some upgrades in the future of quality level but my type preference won't change) symbiants to make a slight comparison with Glara's to show a midhighlevel to highlevel range advies setup.
http://auno.org/ao/equip.php?saveid=10996
I'm a bit to0 lazy to post step by step, so I'll post the reasons why my symbiants are different wherever they differ from Glara's <3.
Eye, ear, rightarm, rightwrist, left and right hand are the same.
First of all, my brain is a support. Can first off use the addition of the nanoskills the int/psy give. Sense is always a bonus (adds ranged weapon skill and helps with armor). Ranged init which is imo the only benefit of Artillery is kind of useless atm (1076 selfed ranged init with 15% crit scope in, so still 1/1 on full def.) The nano init, nanopo0l, nanoresist and max nano are all useful in regards to our final heal, Beauty of Life. And as we have ugly dark blue NR, the more NR we get the better (especially if you're a pvper).
For chest I've finally settled on Artillery. My main reasons being it adds Str, Sta, and Sense. It has with it the nanoskills and hp mods that are also must haves. So I went for attribute trickle down when deciding here (6-7months ago I used infantry or support) as to get trickle down adds to pistol and more importantly fullauto.
The main reason I went support in my left arm rather than infantry was the choice of add off or nano cost reduce. While I am very adequately served in the AR modification department, I lack in the healing. So I decided to work with my head symb and go support to better support beauty of life.
Artillery waist, 100%. Fullauto being the main reason. Second is the agility and stamina modifiers, evades and max hp.
I still havent decided on whether or not to switch my implant for infantry or not. The small modification of plus damage is tantalizing as well as the shielding. But I'm lazy and can't decide if it's worth giving up the nanoresist or not.
I picked Artillery for my thigh. Evades, agility, and runspeed. Hell the damn thing has adventuring to0.
Infantry fo0t for the same reasons you stated. And of course the agility (trickle++) and evades.
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So if you couldn't see, the differences mainly come when the things you'd prefer other symbiants for are no longer necessary (ie adventuring or some other skill you naturally acquire without bo0sting) and therefore allowing you to make a choice to either increase your damage or your survivability.