Hi there.
Let me start off by saying this is from my own experience, but I honestly can't see you enjoying using static infantry and forts for a whole bunch of reasons. Mainly, you'll tend to get trashed the second anyone brings any kind of weapon/psi power that ignores cover. (There are so Yhwh-condemned many of these combinations now it blows my mind).
You won't just struggle to claim objectives - you'll flat out not be able to if they're outside of your deployment zone since it would mean marching unprotected infantry straight into the waiting arms of ap5 or better shooting plus close combat. Again, theres so much of both of these things that you can essentially assume you won't get cover or armor saves for a large bulk of your opponents shooting.
Also speaking from experience - it's dull as hell. You pick a target, shoot, rinse, repeat. No tactical concerns involved other than fire priority - either you wipe out your opponent with shooting or you lose. Believe me when I say this will quickly tire - you leave yourself with no other options. Plus it's kinda hard to do.
My final issue relates to cost - buying armor is much much cheaper in IRL credits than buying up a ton of fort lines.
I guess my opinion is to say all things in moderation. A little armor, a little infantry, a little air power and a little in forts makes a good balance. The second you start taking 1 part of that to the exception of the rest it tends to be expensive, unfun and usually a bit rubbish.
All of that said - forts and infantry do make good fluffy games so if that's your end goal you can't go wrong with the bunkers/bastions kits. The defence lines just look weird to me.
Hope that helps mate.