Depends on the ride you want. Comforts will give a very smooth ride at the expense of a bit more body lean. HD will ride considerably harder.
I put HD on the Volvo, and wish I'd stuck with the comforts, it's too harsh on the highway now.
Check the condition of the rubber bushings on the links on the rear suspension while you are in there, too -- any evidence of shredding on the inside end of the torque strut (upper diagonal from wheel carrier to subframe) means you need new ones. Do both sides if one is bad, I didn't and now need to do the other one. When this link goes bad, the toe on the rear wheel changes with torque, so that the rear end moves on acceleration and deceleration. Makes it hard to drive.
If you just have vague and wandering steering, get an alignment done up front using a spreader bar. If the guy at the alignment place looks blank when you say "spreader bar", take it someplace else, as setting the front toe without the spreader causes incorrect toe-in (too much) and the car will feel like an elephant on rollerskates.
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!