I'd agree motivation prevention seems our primary weakness due to an average lack of speed and numbers. If my opponent's have marker-based motivations, they're usually able to speed into the middle and grab their first few by the time my troops are just arriving in No Man's Land.
In my last game, it felt like my Teknes friend had already searched a little over half of his 10 Treasure Hunt tokens by about halfway through the 3rd round, just as I was passing the 2 Burn It Down tokens I had placed on my own edge of the middle. I ended up lucking out that game, however, as his last 2 real objectives ended up being located safely behind those 2 tokens of mine, and were positioned just right alongside impassible terrain that his approach was really limited... and completely blocked by the bulk of my force. I waited until the last moment to grab my tokens so as to milk that initiative bonus and block him for as long as possible, winning with just 1 Morale left. If either of those tokens had instead been where one of the fakes he had easily searched earlier was, the game would have likely ended a couple turns earlier and I wouldn't have even had a chance.
For deciding motivations, my group tends to roll for motivations now as otherwise we would almost always pick the same ones that we find the easiest.
I'm usually happy to end up with any of the 3 that involve placing objective markers since it also forces my opponent towards their locations if he wants to stop me from otherwise getting them. While I sometimes cringe at our kill-based objectives because they force me to have to run after my opponent's army and can even get in the way at times.
My personal rankings for the motivations with my Hadross:
1. Burn it Down - easy enough to get 3, sometimes 4 near each other with half being on my side of the middle. Wait for 3rd turn is no problem as that's usually when I'm first able to roll up to them.
2. Treasure Hunt - like Burn it Down with ease to cluster them in one area but randomness can make accomplishing it iffy.
3. Land Grab - like the above but lower on the list because it's further to walk. Could be fun to slingshot a shark to a lone marker via taxi crab and decent scent/rage rolls, but that only works one game before regular opponents anticipate it.
4. Sever the Head - simplest of the kill-based motivations on already priority targets, but lower morale bonus than other motivations.
5. Unstoppable Advance - kinda like Land Grab but harder conditions and a longer walk.
6. Personal Gain - not a fan of putting my leaders/specialists on the frontline where they're more exposed as they usually play a ranged support role instead. It is possible for a taxi crab to move them into position so they can immediately do the objective when they activate, which often seems a better choice than sprinting or waiting a turn and hoping that target is still alive and adjacent. And, targets also sometimes end up as 'hostages' against my attacks and oracle nuke since killing them early forfeits those valuable morale points.
This is with us having lists already prepared before rolling for our motivations. Not sure if others have tried playing that the other way around.
How about you, which motivation(s) do you usually play with?